One of the main reasons for recruiting slaves and later Africans to serve in the West India Regiments was their ability to resist disease.The data collected by the War Office proves they were correct in this assessment. In 1838 the government published a Statistical Report on the Sickness, Mortality, & Invaliding among the troops in the West Indies prepared from the records of the Army Medical Department and War-Office Returns (London: W. Clowes & Sons, 1838). It conclusively showed that average mortality for black troops in all British West Indian possessions was only 4% per year between 1816 and 1836. Among white soldiers mortality varied between islands: 8.4% in Guiana, 10.6% in Trinidad, 12.2% in St. Lucia, 14.3 % in Jamaica, and 15.2% in Tobago, but was consistently higher than among black troops. In epidemic years it could reach 30%.
The biggest killers of white troops were the tropical diseases (malaria and yellow fever) to which black troops had either partial or total immunity. Governor of Tobago, Sir William Young, was therefore justified when he observed ‘that negro soldiers, under a climate natural and congenial to their temperament and habits, will go through the fatigues of service in the West Indies with less liability to sufferance, disease, and premature death, than Europeans.’
 Sir William Young, The West-India Common-Place book (London: Richard Phillips, 1807), 214