****SPOILERS*** Story of the 3rd armored division in it's battles from the breakout from Saint Lo in Northern France to the teeth of the what was called impregnable 350 mile Siegfried Line. That's on the German Belgium & French border with tough and indestructible , he never as much got a scratch during entire movie, Staff Sgt. Francis Aloysius, or just "Sully" to his fellow GI's, Sullivan played by the ruggedly handsome Steve Cochran. It's Sully's leadership and determination that in fact has his tank unit breach the Sigfried Line and make possible the invasion of Germany in late 1944 but it came at a steep price. With just the US Military, not including the British Canadian & French allies, suffering well over 200,000 casualties, with some 50,000 KIA, in the process.
Hated by his men at first for driving them for days without sleep against the far less in number but more superior in experience and firepower & experience German Panzer units who's kill ratio was something like 10 to 1 against US armor. Never the less the spearhead 3rd armored reached the Sigfried Line with it's massive tank traps bunkers and honeycombed with underground tunnels way ahead of schedule just before the winter set in. And for some five months fought a seesaw and stalemate battle with the German forces that cost it the loss of some 75% of it's men and almost all its tanks that were quickly replaced which the German losses weren't. During that time it was "Sully" who kept his unit, the 3rd armored, together by leading from the front, not the back, in his lead tank that really inspired his men. The one person who hated "Sully's" guts the most Pvt. Danny Klowicz, Paul Picerni,soon realized what a real fine "Joe" he really was by giving credit to his battle hardened men. That in a letter to his CO. the Sleeping, whom "Sully woke up with a stiff kick in the butt, Capt. Bob Horner played by Robert Horton, who at age 91 is still round with us today, giving them all the glory in his drive to Siegfried Line without once mentioning himself.
There's also in "Sully's unit German born American GI Heinrich "Heinie" Weinburger, Robert Boon, who's main reason for being in the US Army is to free his grandparents from living under the Nazi dictatorship. It was when "Heinie's" grandparents were freed that the stone faced and unfeeling Sgt. "Sully" broke down for the first and only time in the movie and showed, what seemed to be almost impossible for him, genuine emotion even though after all they were Germans. The screenplay was partly written by Samual "Sam" Fuller who some 30 years later wrote and directed a very similar film, this time in living color not black and white, about the 1944-45 war in Western Europe "the Big Red One" that in real life back in WWII he was an actual member of.