Jachman was born on December 14, 1922, in in Berlin, Germany, and moved with his family to Baltimore, Maryland, when he was two years old. Jachman graduated from Baltimore City College High School in 1939 and enlisted in the U.S. Army in November 1942.
Serving as a sergeant in the 513th Parachute Infantry Regiment, Jachman and his company were pinned down by enemy artillery, mortar, small arms fire and two hostile tanks that attacked the unit during the Battle of Flamierge in Belgium on January 4, 1945.
On January 4, 1945, with his unit having suffered heavy casualties, Jachman left his place of cover, dashed across open ground through a hail of fire and grabbed a bazooka from a fallen comrade. He then advanced on the German tanks, firing the bazooka and forcing both tanks to withdraw from combat. Jachman's heroic action, in which he suffered fatal wounds, disrupted the enemy attack and his galantry was rewarded posthumously with the Medal of Honor, the United States’ highest military decoration.
Years later, the town of Flamierge erected a statue honoring an unknown brave American soldier who had stood fighting to save the village. When a search of Army records established that this soldier was Staff Sergeant Jachman, his name was added to the statue. Today, the Staff Sgt. Isadore Jachman Armory is located in Owings Mills, Maryland.
Jachman's Medal of Honor was awarded to his family in June 1950. The citation reads:
Sources: Jewish Recipients of the Congressional Medal of Honor, compiled by Seymour "Sy" Brody;
Congressional Medal of Honor Society.