Although the skilful combination of these arms had always been important, the threads of the modern combined arms battle had emerged by the end of World War One and were knotted together firmly during World War Two.
'Air power ... became entwined with the combined-arms battle on the ground.'
As weapons grew more complex and their appetite for ammunition increased, so more soldiers were concerned with supply, maintenance and repair. Those actually doing duty at ‘the sharp end of war’ became a smaller proportion of the whole army, and their personal accounts often emphasise the sharp contrast between the old-fashioned savagery of their lives and the more comfortable ‘world of the rear’.
During World War Two growing numbers of armoured vehicles appeared on the battlefield, some of them tanks, mounting guns designed to destroy other tanks; some were armoured personnel carriers, giving infantry the protection of armour, and others were self-propelled guns, artillery pieces with their own inherent mobility and protection. Air power, which had effectively made its debut in World War One, became entwined with the combined-arms battle on the ground.
Of course personal weapons remained important, and there were theatres of war like Burma when terrain and climate gave them added importance. But in the second half of the 20th century the crew-served weapon – like the artillery piece, anti-tank gun and machine gun – vied with the armoured vehicle to dominate the battlefield.