After the attack on Pearl Harbor, Bachenheimer volunteered for military service (13 December 1941), and in May 1942 he was allocated to the 504th Infantry Regiment after successfully obtaining his parachuting certificate.
In August 1942, he was transferred to Fort Bragg, North Carolina together with the 504th Parachute Infantry Regiment which was attached to the 82nd Airborne Division.
While the 504th was training at Fort Bragg, Bachenheimer, fluent in German, taught an intelligence class, where he would read out of a German infantry training manual.
Bachenheimer was granted U.S. citizenship on 23 October 1942 by the United States district court of Atlanta, Georgia, his petition for naturalization described him as a 5 ft 10, 160 lbs white male with brown hair and brown eyes, ruddy complexion, exhibiting a small scar on the tip of the chin.
On 23 March 1943, in Fayetteville, Cumberland County, North Carolina, he married Ethel Lou Murfield, whom he called Penny, from Fullerton, California who at the time was working for the Douglas Aircraft Company as a timekeeper.

Bachenheimer took part in Operation Husky, fought in the battles for Salerno and Anzio, where his bravery behind enemy lines made him a legend in the 82nd Airborne Division, earning him the nickname of The Legendary Paratrooper.
From 1942 to 1944, Bachenheimer was the subject of articles in newspapers such as Star and Stripes, Collier's Weekly and the Los Angeles Times, and some of his exploits were broadcast in radio dispatches.

In action during Operation Market Garden, he landed near Grave, the Netherlands, on 17 September 1944.
After successfully avoiding being captured by a band of German soldiers, he reorganized the Dutch underground organizations and went on to become the leader (with the underground rank of Major) of the Dutch resistance group in Nijmegen called K.P. (Knokploegen, or Fist-Fighters, part of the newly formed Netherlands Forces of the Interior, Prince Bernhard led as chief commander), where he gained the name of The G.I. General, his army was known as The Free Netherlands Army, a Battalion consisted of more than three hundred fighters.
His partisans dubbed him Kommandant, Bachenheimers's HQ was set up in a steel factory situated in Groenestraat, south-west part of Nijmegen, by the end of September, Bachenheimer had moved his HQ to an infant school situated further south of the steel factory.
Bachenheimer's second-in-command, two other 504th paratroopers, were known as Bill One (Willard M. Strunk of Abilene, Kansas) and Bill Two (Bill Zeller of Pittsburgh, Pennsylvania, killed in action, Apr 7, 1945).
Bachenheimer's resistance group successfully gathered intelligence about the occupation forces and the information was then transmitted forward to the 82nd Airborne Division.

For his heroic actions in Nijmegen, Bachenheimer was recommended for a battlefield commission and was directed to report to division for an interview by a board of officers, on his way to his interview he picked up an helmet with a first lieutenant's bar on it instead of his own helmet, he was sent back for reconsideration.
Finally Bachenheimer agreed to a battlefield commission as a second Lieutenant.

On the night of 11–12 October, he volunteered to accompany British intelligence officer Captain Peter Baker across the Waal river at Tiel to contact the Ebbens family, the IS 9's mission, the last under the command of James Langley, was to deploy Operation codenamed the Windmill Line on site (The Ebbens's family farm, near the village of Drumpt), bringing back British paratroopers hidden by Dutch resistance in the Arnhem area (Ede, Netherlands) safely to the Allied lines using guides.
Bachenheimer was also determined to establish telephone contact between areas of Germany and the Netherlands opposite his divisional front.
But both men disobeyed a written order from Major Airey Neave (codenamed Saturday) to remain in military uniform and not leave the safe house in daylight.
They went for a walk in plain clothes and were spotted by German troops passing nearby.
Operation Windm
After the attack on Pearl Harbor, Bachenheimer volunteered for military service (13 December 1941), and in May 1942 he was allocated to the 504th Infantry Regiment after successfully obtaining his parachuting certificate. In August 1942, he was transferred to Fort Bragg, North Carolina together with the 504th Parachute Infantry Regiment which was attached to the 82nd Airborne Division. While the 504th was training at Fort Bragg, Bachenheimer, fluent in German, taught an intelligence class, where he would read out of a German infantry training manual. Bachenheimer was granted U.S. citizenship on 23 October 1942 by the United States district court of Atlanta, Georgia, his petition for naturalization described him as a 5 ft 10, 160 lbs white male with brown hair and brown eyes, ruddy complexion, exhibiting a small scar on the tip of the chin. On 23 March 1943, in Fayetteville, Cumberland County, North Carolina, he married Ethel Lou Murfield, whom he called Penny, from Fullerton, California who at the time was working for the Douglas Aircraft Company as a timekeeper.
Bachenheimer took part in Operation Husky, fought in the battles for Salerno and Anzio, where his bravery behind enemy lines made him a legend in the 82nd Airborne Division, earning him the nickname of The Legendary Paratrooper. From 1942 to 1944, Bachenheimer was the subject of articles in newspapers such as Star and Stripes, Collier's Weekly and the Los Angeles Times, and some of his exploits were broadcast in radio dispatches.
In action during Operation Market Garden, he landed near Grave, the Netherlands, on 17 September 1944. After successfully avoiding being captured by a band of German soldiers, he reorganized the Dutch underground organizations and went on to become the leader (with the underground rank of Major) of the Dutch resistance group in Nijmegen called K.P. (Knokploegen, or Fist-Fighters, part of the newly formed Netherlands Forces of the Interior, Prince Bernhard led as chief commander), where he gained the name of The G.I. General, his army was known as The Free Netherlands Army, a Battalion consisted of more than three hundred fighters. His partisans dubbed him Kommandant, Bachenheimers's HQ was set up in a steel factory situated in Groenestraat, south-west part of Nijmegen, by the end of September, Bachenheimer had moved his HQ to an infant school situated further south of the steel factory. Bachenheimer's second-in-command, two other 504th paratroopers, were known as Bill One (Willard M. Strunk of Abilene, Kansas) and Bill Two (Bill Zeller of Pittsburgh, Pennsylvania, killed in action, Apr 7, 1945). Bachenheimer's resistance group successfully gathered intelligence about the occupation forces and the information was then transmitted forward to the 82nd Airborne Division.
For his heroic actions in Nijmegen, Bachenheimer was recommended for a battlefield commission and was directed to report to division for an interview by a board of officers, on his way to his interview he picked up an helmet with a first lieutenant's bar on it instead of his own helmet, he was sent back for reconsideration. Finally Bachenheimer agreed to a battlefield commission as a second Lieutenant.
On the night of 11–12 October, he volunteered to accompany British intelligence officer Captain Peter Baker across the Waal river at Tiel to contact the Ebbens family, the IS 9's mission, the last under the command of James Langley, was to deploy Operation codenamed the Windmill Line on site (The Ebbens's family farm, near the village of Drumpt), bringing back British paratroopers hidden by Dutch resistance in the Arnhem area (Ede, Netherlands) safely to the Allied lines using guides. Bachenheimer was also determined to establish telephone contact between areas of Germany and the Netherlands opposite his divisional front. But both men disobeyed a written order from Major Airey Neave (codenamed Saturday) to remain in military uniform and not leave the safe house in daylight. They went for a walk in plain clothes and were spotted by German troops passing nearby. Operation Windm
Theodore Bachenheimer