By Kevin Deutsch

On a crisp autumn day in 1935, Werner Oppenheimer, 13, walked into his school in Germany and noticed a new sign above the entrance. He gasped as he read it, because it meant the old way of life — the Germany his family had fought for and loved — was gone.

Adolph Hitler Realgymnasium, the sign read in bold, German lettering. Inside the school, changes were more extreme. Teachers now made students, even Jewish ones, sing Nazi songs with lyrics like “When Jewish blood spurts off the knife, things will be twice as good.”

The songs, the anti-Jewish laws, the vicious Nazi rhetoric; all of it made Werner sick. Even now, while recounting his childhood from the comfort of his Riverdale apartment, Mr. Oppenheimer’s voice trembles with anger.

“Everything changed, the old Germany was gone,” said Mr. Oppenheimer, 87. “I had to help fight them.”

After escaping to America with his family shortly before the war, Mr. Oppenheimer didn’t just fight the Nazis. He made history.

The young soldier was among a group of 10,000 troops who came to be known as the Ritchie Boys. Largely Jewish, German and new to America, the group returned to Europe in U.S. Army uniforms to wage psychological warfare against the Nazis.

Mr. Oppenheimer shared his World War II story in advance of Veteran’s Day — a time when the ex-soldier is reminded of the sacrifices made by local Jewish vets who took on Hitler’s regime.

Trained at Camp Ritchie, in Maryland, Sergeant Oppenheimer and his fellow soldiers were chosen for their intelligence, background and mastery of German language and culture.

Grueling coursework taught them the minutest details of the German military, from uniform insignias and medals to the weapons and vehicles used by each unit.

“I knew the German army better than the Germans did,” Mr. Oppenheimer said, and in 1943, he shipped off to Europe and put his training to use.

Trailing Gen. George Patton’s armored troops, Mr. Oppenheimer, then in his early 20s, worked with a team of five men — four of them Jewish — to interrogate soldiers captured at the front.