[4] While on leave in Cairo, Egypt, Sadler convinced members of the recently assembled Long Range Desert Group (LRDG) that he could serve as their truck convoys' celestial navigator.

[5] In the July 1942 raid on the Sidi Haneish Airfield in Egypt, Sadler navigated eighteen jeeps, each armed with four Vickers K machine guns, to destroy thirty-seven German aircraft.

[5] In January 1943, SAS founder David Stirling sought to lead a small group through the Tebaga Gap and meet with the British First Army for Operations Vulcan and Strike against Axis forces in Tunis, Tunisia.

While Stirling and ten of the soldiers were captured by German forces, Sadler escaped with two others, walking 110 mi (177 km) without food and water until they reached the French Foreign Legion and American 26th Infantry Regiment in Tozeur, Tunisia.

Lieutenant Colonel John W. Bowen suspected the trio were German spies, but Sadler eventually negotiated his release to join the British Eighth Army for the remainder of the Western Desert campaign.

[7] In August 1944, he parachuted into France as part of Operation Houndsworth and was awarded the Military Cross for killing two German machine gun crews using an armed jeep behind enemy lines.

[5] In 2022, Tom Shankland directed SAS: Rogue Heroes, a historical drama television series about the Special Air Service's Western Desert Campaign during the Second World War based on Ben Macintyre's 2016 book of the same name.