A fundamental component of Britains early success, naval impressment not only kept the Royal Navy afloatit helped to make an empire. In total numbers, impressed seamen were second only to enslaved Africans as the largest group of forced labourers in the eighteenth century.

In The Evil Necessity, Denver Brunsman describes in vivid detail the experience of impressment for Atlantic seafarers and their families. Brunsman reveals how forced service robbed approximately 250,000 mariners of their livelihoods, and, not infrequently, their lives, while also devastating Atlantic seaport communities and the loved ones who were left behind. Press gangs, consisting of a navy officer backed by sailors and occasionally local toughs, often used violence or the threat of violence to supply the skilled manpower necessary to establish and maintain British naval supremacy. Moreover, impressments helped to unite Britain and its Atlantic coastal territories in a common system of maritime defence unmatched by any other European empire.

Drawing on ships logs, merchants papers, personal letters and diaries, as well as engravings, political texts, and sea ballads, Brunsman shows how ultimately the controversy over impressment contributed to the American Revolution and served as a leading cause of the War of 1812.