The story of the ill-fated bomb plot in Nazi Germany on 20 July 1944, is one of the most famous of the whole war, but conspiratorial groups planning a coup of some kind had existed in the German Army and the military intelligence organization (the Abwehr) since 1938.

Plans to stage a coup and prevent Hitler from launching a new world war were developed in 1938 and 1939, but were aborted. This first military resistance group delayed their plans after Hitler's extreme popularity following the unexpectedly fast success in the battle for France.

In 1941 a new conspiratorial group formed, but little could be done against Hitler while his armies advanced triumphantly into the western Soviet Union through 1941 and 1942. During 1942, an effective resistance network was nevertheless rebuilt. Its most important recruit was General Friedrich Olbricht, head of the General Army Office headquarters at the Bendlerblock in central Berlin, who controlled an independent system of communications to reserve units all over Germany.

In late 1942 this group formulated a plan to assassinate Hitler and stage a coup during Hitler's visit to the headquarters of Army Group Centre at Smolensk in March 1943, by placing a bomb on his plane. The bomb did not go off, and a second attempt days later with Hitler at an exhibition of captured Soviet weaponry in Berlin also failed.

Journalist James P Duffy looks into the many attempts to kill Adolf Hitler, resulting in the best known account of each individual assassination plot in existence.