Louis Frank, formerly the army doctor of the Napoleonic campaigns in Egypt who was based in Cairo for five years, published this short memoir in 1802. He observes that the transatlantic slave trade was well known in Europe, but that the transaharan trade to Cairo was much less familiar. He describes how slaves were procured in the Sudan, the caravans of slaves that were forced to cross the Sahara on foot, and the mortality rate (which he suggests was considerable, although still lower than the transatlantic trade). Frank's medical knowledge informed his interest in disease and the procedures (including castration in some cases) to which the enslaved were subject on arrival in Egypt. He also remarks in passing that slaves were bought from the caravans to serve the French army, under Napoleon's orders.