For the past 25 years, British general and vascular surgeon Dr David Nott has volunteered in some of the world’s most dangerous conflict zones. His book War Doctor is a first-hand account of working in war-ravaged countries. This extract details his extraordinary experience working in hospitals in rebel-held east Aleppo, Syria — a place he named Sniper City.

Some days were busier than ­others, and some were so busy that the days merged into the nights and vice-versa.