Ship Maneuvers in Patrick O'Brian's H.M.S. Surprise

(Volume 3 of the Aubrey/Maturin novels)

by C. F. Keller




In this volume Aubrey saves a large fleet of Indiamen from four French fighting ships under Linois. The description of this encounter covers five days, involves two running shootouts, and is probably the most extensive and complicated description of a battle at sea in the entire Aubrey series. As such it gives the best example of how a large number of ships behaved in a lethal engagement with the wind the everpresent limiting factor. For all its importance, the encounter is hard to follow for the interested, but unskilled-in-shipspeak reader. While O'Brian gives enough information to piece together most of the events, several important (even crucial) points beg discussion and probably need comment from O'Brian himself (perhaps in the Newsletter?). This is all the more important because the climax of the affair (the Surprise attempting to cut off the Marengo 74 by crossing its bow) seems faulty. It is hard to believe that the Linois would allow such a crossing move when vearing to port would allow him to sink the Surprise and then reengage the rest at his leisure. Regardless, trying to trace the entire five days' story is great fun. The following is my interpretation of the events as best I can piece them together. It has certain inconsistencies that I cannot figure out (probably errors in my interpretation). Any helpful comments would be appreciated. One assumption (based on repeated O'Brian statements) that has to be made is that the wind is always from the northeast--the so-called "monsoon" wind. Thus all maneuvers assume ships cannot sail more than two points (11.5 deg/point) into the wind. This limits how ships get the "weather gauge" in a battle (i.e. have the advantage by being upwind). (Also, I interpret the phrase, "sailing two points free" to mean the the ship's course is such that it could still sail two points closer to the wind. Thus two points free means that the ship has the wind approximately at right angles on its beam.) The ability to sail "close hauled" into the wind appears to be crucial to whether the last maneuvering (day 5) between Surprise and the Marengo can have taken place as described. Finally, page numbers cited are from the paperback.

First Encounter, Day 1

While sailing to Calcutta (returning along the south coast of Sumatra-from an earlier location (p. 267) given as 5 S, 103 E), Jack Aubrey at 89 E encounters the China Fleet which is apparently sailing west (p.274; also Aubrey's comments in letter to Sophie, p. 246). The "fleet" has many small ships with local destinations but also 16 larger "Indiamen" bound from Canton to London. It is these that will play a key role in the encounter to come. After a sumptuous dinner aboard Lushington, Jack sails away in Surprise. Which direction is not told, but it is reasonable to assume towards Calcutta. Now Calcutta is at roughly the same longitude as where the China fleet is sighted, 88-89 E, and the "monsoon" north east winds might be expected to occur near India. The China fleet's route is not told but, if it went thru the Strait of Malacca, it would cross 89 E at the latitude of Sri Lanka or a bit south. Thus I assume Jack is sailing north from about this latitude. However, while this interpretation makes sense, Jack sights the French with the China fleet northeast! Thus, POB keeps Surprise south for purposes of this engagement.

Day 2

We are told nothing about this day. Presumably Jack has left the Indiamen and is heading north to Calcutta, his stated destination. This is a problem because later events put him south of the China Fleet! In fact what follows seems to put the China fleet east and north of Aubrey when he sights the French on Day 3.

Day 3

The story switches from day 1 to day 3 with "Two days later...."(p. 281). This day finds Jack remounting a mast with Surprise on a larboard tack (wind from the left) heading pretty much east-southeast. (Larboard tack, or course, could be any direction from ESE to SW, but the following description of the chase by the French shows Surprise to be heading nearly south.) Linois' five French ships are sighted (p. 281) "in line abreast strung out to sweep 20 miles of sea standing directly for the path the slow China fleet would traverse the next day".

They are:

  • Marengo, 74 (24 and 36 pounders)
  • Belle Poule, 40 (18 pounders)
  • Semillante, 36 (12 pounders)
  • Berceau, a 22-gun corvette,
  • and a brig.

    As the French are "on the larboard bow" heading northwest (on a starboard tack), Surprise must be headed in a southerly direction (See accompanying Chart). Jack "hauls his wind" (turns to port into the wind and comes thru stays onto a similar starboard tack [marked 1 on Chart 3-1]) "close-hauled and heading north, leaning far over to larboard" (p. 283) - probably a bit west of north unless Surprise can sail closer to the wind than most. Recall that on the previous page the wind was characterized as a "steady north-east wind".

    Linois has been aiming for Surprise and now follows "his turn in chase" (8-9 knots which is slower than Surprise, mostly because the French have been at sea longer and their copper-sheathed hulls are growing "weed" that slows them). Then O'Brian makes the confusing remark, "They would never fetch his (Aubrey's) wake unless they tacked, however; they had been too far ahead for that." This means they are on the same tack but slightly down wind. (For Chart 3-1 I have placed all of the French ships downwind from Surprise with the exception of Marengo. If I place Marengo also downwind, I cannot Chart the subsequent manuevers.) At this point Marengo does indeed tack (actually it wears) (p. 286) "close-hauled on a larboard tack" i.e. heading ESE. [See Chart 3-1].

    On p. 287 O'Brian writes: "His present course" (Linois') "was taking Linois straight towards the Indiamen, half a day's sail away to the east". (Their half day subsequent sailing will put them to the northwest.)

    P. 286-- Three ships (Marengo, Berceau, and the brig) stand on the opposite tack (Berceau and the brig are too far to the east to show on Chart 3-1) "meant to cut him off if the frigates managed to head him--grey hounds on either side of a hare, turning him." (Note that all ships are shown on Chart 3-1 as sailing as close to the wind as possible. Thus Belle Poule can't aim for Surprise, but must be content with sailing on a parallel course slightly down wind. Semillante is closer and, while it too cannot sail to windward, its position allows a parallel course close enough to bring Surprise within range of its long guns.)

    Aubrey decides to lead the French southwest--away from the Indiamen, but worries about Linois sending the frigates north anyway, making it hard for him to beat up "tack after tack" past them to the Indiamen. But he decides on a maneuver that might open a gap between the frigates and Marengo through which he could race southwest "running before the wind" (p. 288). The gap to the west occurs because, as we shall see, Surprise tacks east first.

    O'Brian writes that the corvette, Berceau, is "farther to leeward". This must mean that the French were coming up from the south with Berceau west of the rest. Marengo is "running east-south-east" (p. 288) which is a closehauled larboard tack, and so must be to the SSE of Surprise.

    Surprise leads the frigates north by dragging a sail astern in the water to slow its speed, while having all sail set as if trying to escape. Semillante actually gets close enough that its bow chaser can nearly reach Surprise. Surprise "goes about", "up into the wind" (p. 289) turning east [point 2 on Chart 3-1]. The two frigates start to do the same but are signaled from Marengo to stand on NNW instead. Belle Poule is already too far into the wind and has to wear, bringing it closer to Surprise [point 2 on Chart 3-1]. This mistake narrows the gap between Belle Poule and Marengo that the Surprise wants to race through. Both frigates "cross the wake of the Surprise", while the "Marengo...lay on the starboard beam, sailing a parallel course" south of Surprise.

    Then Aubrey makes his move (p. 290)--first "bearing up" (this usually means to sail into the wind--passing through stays, but here I think from the description he wears as the fastest way to come to his new heading. Thus, at the command "hard a-port" which turns the ship to starboard(!), Surprise "turns on its heel" and comes quickly to its new course, SSW, bringing the "wind two points on the quarter" meaning sailing nearly before the wind on a broad reach that fills all sails [point 3 on Chart 3-1]. O'Brian says "she was heading...straight for the potential gap." Marengo bears up and sets a course to intercept Surprise "at some point in the southwest" (p. 291). This makes sense. Surprise has gone east to let the two frigates pass north behind her "cutting her wake". The gap has opened because Marengo is east and south of Surprise on "a parallel course". Surprise turns quickly and heads through the gap and Marengo turns to head him off. Meanwhile, Belle Poule and Semillante turn [point 3 on Chart 3-1] and come "pelting down" after Surprise, closing the gap. Surprise wins the race--sails through, heading roughly SSW towards the corvette, Berceau (bearing SE, on the larboard bow, p. 294 [not shown on Chart]). Surprise sails past, exchanging fire with Berceau. Surprise comes about in the darkness at 8 bells (p. 298) and heads north for the China fleet.

    Day 4

    Daylight finds the Surprise approaching the China Fleet (some forty vessels), but they are discovered by the French brig in the east, and it signals the rest of the French to the south. There follows a splendid series of maneuvers, some of which are a bit difficult to understand. The fifteen Indiamen form a line of battle with a number of ruses to fool the French into thinking there is some form of armed escort. The French lie "east by south" (p. 306). The British line comes about "heading SE with larboard tacks aboard, a line of ships a mile and a half long" (p. 308) [see Chart 4-1, point 1].

    At first Surprise leads the line while Linois gathers the French ships. Aubrey gives the order "tack in succession" (p. 311) which they do (point 2), following Surprise, and all head back north. For future reference, their order is the following:

    1. Alfred, 2. Coutts, 3. Wexford, 4. Lushington, 5. Ganges, 6. Exeter, 7. Abergavenny, (Surprise), 8. Addington, 9. Bombay Castel, 10. Camden, 11. Cumberland, 12. Hope, 13. Royal George, 14. Dorset, and 15. Ocean.

    The Indiamen are on "the starboard tack with the wind two points free" (heading roughly NW - 8 points from the wind which we take here to be fairly constant out of the northeast). As Surprise passes the last ship Aubrey is told: "'Sir, Linois is putting about, if you please.' 'So he is,' said Jack, glancing aft. 'He has fetched our wake at last.'" (point 3) NOTE: this remark is confusing since the French must be fairly upwind, as attested to by the following text that says they lie 3 points on the quarter [Chart 4-1]: "Linois had been continually manoeuvring to gain the wind, and to gather his forces, making short tacks, standing now towards the Indiamen, now from them" (p. 312).

    Linois is now to windward and coming up fast under full sail. Jack has the Surprise enter the 8th position midway in the line. "Linois is five miles away, coming after them from the eastwards on the same tack..." (p. 313). The French line is so close astern that it is obscured by the line when Surprise pulls into its position. NOTE: again confusing since if they bear 3 points on the quarter, must they not be fairly easy to see without the following ship blocking the view? Actually "they bore three points on the quarter" (meaning well astern but angling slightly in - see Chart 4-1, point 3).

    Now Audrey tries a bluff. He waits until "Semillante was at extreme random-shot range of the rear of the line." NOTE: I took this to be a about a mile - not sure of this distance. Then, he has the line "edge away one point" (from the wind--more westerly, "wind just before the beam") [Chart 4-1, point 4]. Note: this last remark doesn't make sense. We have been told that the line is sailing two points free which is nearly NW. Thus the wind is directly on the beam. Now they edge away from the wind another point which would take the wind aft. How can it be "just before the beam"? This is done because Aubrey knows these ships are not used to precision maneuvers. Edging downwind a point (11.5 degrees) makes it easier for them to initiate the next command. After making sure all is in order he has the entire line "wear all together: course south-east by east" (p. 314) [Chart 4-1, point 5]. This reverses the order front to back and sets them on a collision course with the French. "Ahead of them now, and broad on the larboard bow, there was the French squadron in a rigid line... The two lines were drawing together at a combined speed of fourteen knots: in less than five minutes they would be within range."

    Note two things. First, to make this work the French would reasonably have followed the China fleet's turn [Chart 4-1, point 4]. Second, by wearing all together the China fleet is no longer sailing "in line" since wearing to a new heading leaves their relative orientation the same as before but their heading different (see Chart 4-2). In fact they are now sailing en enchelon or roughly side by side!

    The French "haul their wind, heading north-north-west and decline the engagement" (p. 316) [Chart 4-1, point 6]. This takes them past the British, angling off towards the north a bit. Aubrey then orders "tack in succession" and the entire line returns toward its original NW heading and prepares to stop for the night.

    Now, "tack in succession" means that each ship tacks when it comes up to the place where the lead ship tacked (see the detailed description of this on p. 311). But the British ships have gotten onto the new course not by tacking in succession but by simultaneous wearing. Thus they cannot tack in succession in the normal sense (turning exactly where the ship ahead of them turned) since they are no longer sailing in a line, but sailing more abreast. Thus they will have to pay off to starboard slightly, each heading for the point where the first ship tacked (see detail in Chart 4-2).

    The China fleet sets up for the night, but here O'Brian confuses me yet another time for he has Audrey say that Linois "will spend the night plying to windward while we lie to" (p. 316). Since, in declining the engagement, the French headed NNW at a distance of less than five miles, they need only a single larboard tack to go upwind of the China fleet line that will remain stationary all night. Can anyone explain this?

    Day 5

    This is the climax of the encounter, and is perhaps the most difficult to understand (I would greatly appreciate comments). After attempting to work out all the details, I have decided that there are some irreconcilable contradictions, but, if one suspends judgment a bit, the thing hangs together reasonably well, and is a rousing tale.

    The day begins with Linois' line upwind, parallel to the British line "with their heads north-west... and three miles apart" (p. 317). The wind is still "the unvarying north-east monsoon" (p. 318). The French send Semillante "down to cannon range to reconnoiter and return: (Question - how is this done without much tacking?) but make no move, and so after breakfast Aubrey signals, and the China line stands away "to the westward... on the starboard tack" (p. 319). This is not a definitive direction. However, later ship movements seem to work out best if the line is a point south of strict northwest.

    At once the French ships "wore round on the opposite tack, slanting down southwards for the Indiamen" [Chart 5-1, point 1], suddenly crowding sail, and racing for a location four ships up from the rear of the line (point 2). Linois means to cut through the line, and then come up the leeward side where the leeward lean of his ship will allow him to open his lower gun ports and use his 36 lb guns - a deadly maneuver. Aubrey answers with two moves. First, he has the entire line "tack in succession" and sail south as fast as possible to engage (point 2). Second, he takes the Surprise out of the line (it is roughly in the middle - eight ships from the rear [point 2]), and races to cut off Marengo, hoping to either cause him to shear away, thus ending the engagement momentarily, or if Marengo keeps straght on, to cross Marengo's bow: "Harrowby, lay me athwart the Marengo's hawse" (p. 321).

    The geometry of the encounter must satisfy three main constraints:

    First, the French line starting location must be far enough south and/or east to avoid being within range of the vanguard ships that have already tacked and are racing south; and it must be approaching from north of the wind direction because O'Brian says Marengo is leaning away from the wind so much that its lower starboard gun ports must be kept closed.

    Second, the French line must cross the British line ahead of the last four ships, yet Surprise is only four ships farther up the line (about 1/3 mile) and so will come down to that point fairly quickly, especially since that point itself is moving up as the China line sails along. Thus it would appear that the French have the longer distance to travel.

    Third, Surprise must approach Marengo so that its guns can't bear on Marengo, but Marengo's guns can bear on Surprise. This can only happen if Marengo is ahead of Surprise and crossing her bow, which means that Surprise has the longer distance to travel, violating the second constraint!!?? (Also this means that Surprise must be travelling significantly faster than Marengo. This seems unlikely because earlier POB states that Surprise is faster than the French, unless sailing into the wind when they are before it (p. 287.)

    The last two constraints are hard to reconcile. In Chart 5-1 I do the best I can.

    One more geometry consideration. POB states that at the time that Surprise is passing the third ship behind it, the position is thus [Chart 5-1, point 3]: "On the port bow a long mile away to the north-east" is Marengo. (For reference, the British line is 1.5 miles long) "On the port quarter, still a mile away ... are the British ships that have already tacked and are coming down" (p. 321). This is a triangle about a mile on a side. The base is the British line with the first ships already coming south, with the point Marengo is aiming at rapidly moving northwest. The apex of the triangle is the French line, and somewhere in it is Surprise, which is sailing "close hauled" (this means as close to the wind as possible - roughly 6 points from the wind - SSE) and said to be racing and adding sail. As the ships come together, we get another clue. Marengo fires two cannon at "extreme range" which is about one mile. (We know this because on day 3 we were told that each ship was "surrounded by an invisible ring two miles and more in diameter - the range of their powerful guns." [pp. 291 - 292]). The first falls "a hundred yards out on the larboard beam". The second is "closer and to starboard" (p.322)! This seems to say that Marengo is roughly dead ahead and crossing Surprise's bow allowing ranging shots to land on either side. Thus Surprise has the longer distance to travel, and so must be moving faster close-hauled than Marengo is - a curious situation since Marengo has the wind aft.

    As the ships converge, Marengo gets off four broadsides (numbered in Chart 5-2), the first at about a mile range! Just after the last broadside "the rear Indiamen open fire at 1/4 mile" (p. 325) which means Surprise has been angling only slightly away from the line. Soon after this Aubrey tells the helm to "ease off" a point to keep up her speed - she is heavily damaged. Then "half a point" more (point 4). Thus, as he starts to cross Marengo's bow, he is sailing back towards the line, more with the wind.

    Now for some timing. Marengo is probably sailing as fast as it can - 10 knots? This is more than 11 m.p.h. - 11 x 1760 yards / 60 minutes, or 350 yards/min. Since Marengo's broadsides come at 2 minute intervals, the scale here is more than 600 yds between broadsides (Chart 5-2). Actually I have put them closer, as a compromise between distance travelled and cannon range. In the Detail section of Chart 5-2 we see Surprise firing at Marengo. Since the Surprises can fire every 1 min. 20 sec., Marengo travels approximately 400 yards between broadsides. By Surprise's third broadside it is athwart Marengo's bow, now only 200 yards distant and nearly dead in the water (p. 326). Thus, its first broadside would have been delivered when Marengo was about 1,000 yards distant, which would mean that all Marengo's broadsides were delivered at greater distances. Perhaps the answer is that Surprise has fallen off one and a half points and is not crossing Marengo at a right angle. As with much of this account, things only work out approximately.

    To avoid being run down, Surprise gets underway and turns two points more to starboard [Chart 5-1, point 5, and Chart 5-2, detail]. This is 3.5 points (about 40 degrees) free, or 18 degrees south of SW. Half a mile astern the "British van opens fire on Semillante and Belle Poule" (p. 327) [point 5]. Marengo comes along side Surprise at extremely close range, and a few ragged shots are exchanged. Surprise avoids destruction because the rear three Chinamen, led by the Royal George, have left the line and begin to attack Marengo on its windward side! [Chart 5-1, points 4 and 5, and Chart 5-2] Thus a net of British ships threatens to envelope the French.

    The French haul their wind - they wear onto a larboard tack heading ESE away from the British [Chart 5-1, point 6]. As Marengo shears away into the wind, it presents its stern to raking fire. Then it is out of range and racing away. "The French line had worn together: they hauled close to the wind, passed between the converging lines of Indiamen, and stood on" (p. 328).

    Text copywrite 1996 Charles Keller. Please direct comments to him at

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