Blitzkrieg "lightning war" was the key to Germany’s successes on land during the first half of the war, and speed was the essence of blitzkrieg. Aircraft, tanks and motorised infantry were the tools that made it feasible. The thinking behind blitzkrieg was not German. Two British theorists, Maj General J.F.C. Fuller and Captain Basil Liddell Hart, conceived it in response to the stalemate and carnage of World War I. They argued that the internal combustion engine had transformed the pace of battle and needed new strategies. Destroy the enemy’s brain, not the body, they said: make sudden concentrated attacks on the headquarters and communications, not on the mass of the army. The western democracies did not take up these ideas, but the Germans were more open. General Heinz Guderian was a major force behind their new battle plans. In practice, after probing for the enemy’s weak spots, the tanks of a panzer division surged ahead, bypassing the strong points, not tackling them head on, to penetrate deep behind the enemy’s defences and cut up the troops into separate pockets. Air power made a pre-emptive strike to destroy the enemy air force and Ju87 Stuka dive-bombers went with the tanks to give bombing cover and act as swift, highly manoeuvrable artillery. Slow-moving conventional artillery and infantry, only a fraction mechanised followed up to crush the pockets. Blitzkrieg notched up rapid successes for the Germans. Only much later in the war was effective countermeasures developed, mainly by the Russians. In 1941-2 they retreated too rapidly for the Germans to get behind them. And then, at Kursk in 1943, they showed how complex, deep defences could break the impetus of a blitzkrieg attack. Savage Fighting Members of the elite SS Liebstandarte Adolf Hitler, originally the fuehrer’s bodyguard, fight off a fierce Polish counterattack near the Bzura River west of Warsaw. By mid-September, the bulk of the Polish armies were sealed into a series of pockets, unable to break free for the relative safety of south-east Poland.