When Julius Caesar landed on the shores of Britain with his Roman legions, he took a bold and decisive step to ensure the success of his military venture. Ordering his men to march to the edge of the Cliffs of Dover, he commanded them to look down at the water below. To their amazement, they saw every ship in which they had crossed the channel engulfed in flames. Caesar had deliberately cut off any possibility of retreat. Now that his soldiers were unable to return to the continent, there was nothing left for them to do but to advance and conquer! And that is exactly what they did.
Note: This may not be historically accurate. If Caesar burnt his boats (and it looks like he may have) it might have been to keep them from falling into the enemies hands, and the ship burning might have been in Alexandria not Britain. So, this story might best be introduced as a legend.