It was the biggest invasion in history: Operation Barbarossa – Hitler’s blitzkrieg attack in June 1941, designed to overrun Russia before the winter. We know the outcome. We know this proved a fatal decision. We know that war against the Soviet Union, with its vast distances and massive reserves of manpower and industrial capacity, sealed the fate of Nazi Germany.

But Barbarossa came close to success, thanks to the gaping self-inflicted wound of the Stalinist terror. Military historian David Porter marks the 80th anniversary of Hitler’s invasion of European Russia with an in-depth analysis in our special this time.

Also this issue, we look back before the 20th century. Medieval specialist Steve Tibble challenges stereotypical views of the Crusaders – as crude feudal brawlers – to argue there was clear strategic thinking in the 200-year struggle against the odds to defend the Crusader states.

Fred Chiaventone returns with a critical assessment of a famous British disaster in the American wilderness – Braddock’s defeat at Monongahela in 1755 – while Patrick Mercer takes a look at the last French invasion of Britain (in 1797). And John Lock opens a new series on ‘the butterfly effect’ with an assessment of the military impact of the accidental shooting of ‘Stonewall’ Jackson at Chancellorsville in May 1863.