BASTOGNE, Belgium (AP) — The United States, its European allies and a dwindling number of veterans are marking Friday the 80th anniversary of the Battle of the Bulge, one of the most important and deadliest battles in World War II that ended the battle Adolf Hitler led one last offensive and paved the way for the complete defeat of the Nazis.

At dawn on December 16, 1944, more than 200,000 German soldiers destroyed Hitler’s last hopes with an unexpected attack through the dense forests of Belgium and the hilly Ardennes of Luxembourg. Taking advantage of the surprise attack, the cold, freezing weather, and the exhausted U.S. troops, the Germans penetrated so deep into the front that it became known as the Battle of the Bulge.

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It sparked a month of intense and dramatic fighting that ultimately ensured that the Allied advance on Berlin could continue. The US troops, initially outnumbered, delayed the attack in bitter fighting until reinforcements were able to arrive by Christmas and turn the battle around.

For organizational reasons, the commemoration and celebrations began on Friday.

Germany is now an ally of the United States and its war partners in NATO.

Hitler had hoped that the advance would change the course of World War II by forcing U.S. and British troops to sue for peace, thus giving Germany the opportunity to focus on the rapidly advancing Soviet armies in the east to concentrate.

After the end of fighting in the Battle of the Bulge on January 28, 1945, Allied forces invaded Germany, eventually leading to the Nazi surrender and the end of the war in Europe.