Franz-Stefan Gady and Michael Kofman on what Ukraine must do to break through Russian defences

COMBINED-ARMS WARFARE is a deadly ballet choreographed to overwhelm the defender by integrating different combat arms, such as infantry and artillery, and services, such as ground and air forces. Its origins lie in the last two years of the first world war. After years of stalemate, the German Imperial Army adopted innovative tactics to break through the layered Allied defences of the western front and thus out of the attritional deadlock.