] In the light of all this, less than 1000 pounds prize money for being in on the Battle of Trafalgar seems pretty insignificant. It is not like a captain could count on having 20 such opportunities in his career. How did captains acquire their wealth? Did the sensible ones simply save their salary?

No prizes, no prize money. Trafalgar was followed immediately by a storm, in which many of the captured French and Spanish ships, which had been badly damaged, were lost. In addition, what prize money there was had to be shared round to a lot of claimants after a major fleet action.

Prize money was a very hit or miss proposition. Like the US and German submarine commanders of World War II, it was the younger men who got to distinguish themselves individually as hunters. The captains with the best opportunity to get rich were the fairly junior ones commanding frigates or smaller vessels, because they had the best chance of making captures of enemy merchant vessels, commerce raiding warships, or privateers. The right command in the right place could make all the difference, as Harville's lack of good fortune shows.

More senior captains didn't do as well. Fleet actions were few and far between. The post captains who commanded ships of the line spent most of their time blockading French ports. It was hard work, and demanded great seamanship, but it was terribly lacking in incident.

(That, btw, is why most fiction about the Royal Navy in this period deals with officers in command of smaller vessels -- there's just not enough blood and thunder in endless routine cruising off Brest or Toulon. Both Forrester and O'Brien find ways to get Hornblower and Aubery out of the command of a ship of the line to which their seniority would ordinarily entitle them, and Forrester has Hornblower spend much of his time in that command on detached service.)

Admirals were the biggest beneficiary of the system. If you ever flew your flag as a squadron or fleet commander, you got 1/8 of the prize money on all captures by ships under your command.