The general story is that during the Pegasus (spl?) Bridge operation, some German armor started advancing towards the glider troops recently won position. One of the troops had a PIAT, and crawled until he was near enough to the lead tank (something like 4 tanks in total, all older models) to take a shot. He fired, and killed the driver, and in the process stopped the other tanks from advancing. Rather than trying to move the obstruction, the other tanks thought it prudent to retreat given they didn't know exactly what they were facing.
Can someone get me the story online, or if possible, the whole Pegasus Bridge story online? I'll admit freely that I probably goofed somewhere, but its been a good 4 years since I saw the episode on the History Channel about the Pegasus Bridge operation.