Only to discover, when it was too late, that they had practically destroyed the British Army

For years Pitt and Dundas continued to pour men and money into the West Indies against what they were pleased to call brigands. Helped by the climate, the black labourers so recently slaves, and the loyal Mulattoes, led by their own officers, inflicted on Britain the severest defeat that has befallen a British expeditionary force between the days of Elizabeth and the Great War. The full story remained hidden for over a century, until it was unearthed in 1906 by Fortescue, the historian of the British Army. He puts the blame on Pitt and Dundas "who had full warning that on this occasion they would have to fight not only poor, sickly Frenchmen, but the Negro population of the West Indies. Yet they poured their troops into these pestilent islands, in the expectation that thereby they would destroy the power of France, only to discover, when it was too late, that they had practically destroyed the British Army.

....

By the end of 1796, after three years of war, the British had lost in the West Indies 80,000 soldiers including 40,000 actually dead, the latter number exceeding the total losses of Wellington's army from death, discharges, desertion and all causes from the beginning to the end of the Peninsular War. The cost in San Domingo alone had been £300,000 in 1794, £800,000 in 1795, £2,600,000 in 1796, and in January 1797 alone it was more than £700,000. Early in 1797 the British Government decided to withdraw and maintain control only of Mole St Nicholas and the island of Tortuga

C.L.R. James, The Black Jacobins (1938, 2001 edition), 118-9 and 164