Rounding a hilly bend 50 years ago Tuesday, American GIs captured a bridge that was not supposed to exist and crossed a river they hadn't expected to see.

That river was the Rhine, and the battle they kicked off at the Ludendorff Bridge hastened the demise of the Third Reich."In small or large measure, it hearkened the end of the war," said retired U.S. Army Maj. Gen. George Ruhlen, 84, who was an artillery commander a few miles south of Remagen when American troops took the bridge.

Ruhlen, of San Antonio, was one of 600 U.S. and German veterans and their relatives who gathered under clear skies Tuesday for a 50th anniversary ceremony beneath the stone towers that are all that remain of the bridge.

The bridge capture was unplanned. The 27th Armored Infantry Battalion that carried it out was part of the First Army Group, whose role in the Rhineland offensive of February was to reach the river, then proceed south to join with the 3rd Army Group of Gen. George Patton.

The GIs had been told that Hitler had destroyed all bridges over the Rhine. Yet there it was in front of them: a gray railroad trestle spanning the river into the German heartland.

As the Americans prepared to cross, German soldiers on the other side set off a dynamite charge that rocked the structure, but didn't destroy it.

Everything happened so fast that Ruhlen was taken by surprise.

"I heard guns firing on the other side of the hill and I radioed in to ask what was happening," said Ruhlen. "They said they had an observer on the other side of the river and I said, `What river?' I didn't believe it could be the Rhine."

One hundred twenty troops swarmed over the bridge and secured a foothold under the basalt cliffs on the other side. Within a week, Gen. Dwight Eisenhower had poured 25,000 more men, tanks, artillery and trucks across the bridge.

Michael Chinchar, 77, of Saddle River, N.J., captured a tower on the east side of the bridge and was one of 13 soldiers to get the Distinguished Service Cross.

Gazing at the basalt cliffs across the river Tuesday, Chinchar recalled leading his men across and throwing themselves into an abandoned German trench.

"It's like a dream - but one you can't forget," he said.

News of the bridge's capture sent defense industry stocks plunging on Wall Street. Hitler fired Field Marshal Gerd von Rundstedt, commander of the Western front, and a drumhead martial court executed four German officers, including Hans Scheller.

Scheller's son, Gerd, was at Tuesday's ceremony. "In the name of two postwar generations, I want to thank the Americans for acting as resolutely as they did on March 7, 1945," he said.

Hitler threw everything he could at the Ludendorff Bridge - 367 warplanes, V-2 rockets, howitzers, frogmen and even an experimental jet fighter - the ME-262. Hundreds of GIs died.

The bridge finally collapsed March 17, taking 28 Army Engineers down with it. By then the Americans had built two pontoon bridges over the Rhine.

The bridge, built during World War I to supply the Western front, was never rebuilt. Each year 25,000 people visit the Peace Museum that former Remagen Mayor Hans Peter Kuerten established in the stone towers by selling pieces of the bridge, mostly to U.S. veterans.

"It meant the end of the bomb attacks for us," recalled Kuerten. "It meant the collapse of the western front."

Walter Schaefer-Kehnert, a university professor who was a commander of the Wehrmacht's 11th Armored Division, said Germans should always be grateful for the American help that enabled the rebirth of postwar Germany.

"We must recognize that a long and lasting friendship started at this place."