Second World War

In 1940 and 1941, after a spell in Egypt and the Sudan, he would see action in Eritrea and Abyssinia as part of the East African Campaign.^[3] It is here that he commanded the 2nd West Yorkshire Regiment. He was awarded the MC in Keren for successfully capturing the Dologorodoc Fort, a former Italian stronghold. Weeks later, he would be awarded a DSO for repelling a heavy Italian offensive at Tobruk, where he sustained a bullet wound to the head.

After recovering from his wound, he was posted to Sicily where he would plan the strategic allied invasion. Here, his jeep would be hit by a shell killing his driver and wounding Osborn.

After recovering in London, he was posted to the War Office in 1943, it is here that he would plan the forthcoming D-Day invasion. Later in April 1944 he joined the staff of the 2nd British Army Headquarters, where he would serve under the command of Selwyn Lloyd. Later this year, he would land in Normandy with the 2nd British Army.

By 1945, the allied forces were rapidly advancing into Germany, under the command of General Sir Miles Dempsey he would be one of the first Allied military personnel to enter the concentration camp at Belsen.

By May 1945, Osborn had learned that an individual bearing a stark resemblance to SS leader Heinrich Himmler, had entered an allied interrogation camp, perhaps to surrender to the Allies or seek refuge. Upon being informed of this news Osborn, headed straight to the whereabouts of the suspected individual, identified him, and subsequently apprehended him accompanied by a Lieutenant-Colonel "Spud" Murphy. Osborn and Murphy, would take Himmler to Army HQ, where Himmler is believed to have committed suicide by the means of hiding a potassium cyanide capsule under his tongue and subsequently ingesting it before interrogation could begin.

He was then appointed second in command of the 1st Battalion West Yorkshire Regiment in Burma as part of the South-East Asian theatre. Following victory in the Far East he commanded the 2nd Battalion in Indonesia and Malaya.

Malayan Emergency

After serving at posts in Greece and Vienna, he would also play a significant role in the Malayan Emergency commanding the 1st Battalion, The Federation Regiment in operations across Malaya in 1958, aiding the British effort to prevent the rise of communism in the area. Come the end of his service in Malaya, he would be awarded the PJK Meritorious Service medal.^[4]

Later career

Several years later, in 1961 Osborn attended the Imperial Defence College, London, where he would become acquainted with King Hussain of Jordan and the Shah of Iran.