To many people in the UK, D-Day (6 June) and the following six weeks of fighting in Normandy is the most obvious 'significant battle': it allowed the rapid liberation of western Europe.

The technical complexities of putting huge, largely untried armies across the Channel and supplying them there were very great. The Germans thought that they had a good chance to repel any invasion.

After D-Day Hitler chose to mount a stubborn defence of the Normandy region, and when the main American breakout came, in late July, the burned-out defending forces had no option but to beat a rapid retreat to the German border.