Complex sentence: Following the Dunkirk evacuation in 1940, there was a critical shortage of weapons in Britain; there was a particular scarcity of anti-tank weapons, many of which had been left in France.
Split into simpler sentences: Following the Dunkirk evacuation in 1940, Britain faced a critical shortage of weapons. In particular, there was a severe scarcity of anti-tank weapons, many of which had to be left behind in France.