Burnt your boats

how did the english expression "To have burnt your boats" originate.The expression means that there is no turning back.

The short answer is that you are correct, and the phrase has been updated to "burn your bridges." Both phrases are current and mean the same thing. The Roman army, and others of the time, would sometimes deposit troops on the other side of the water by boat and then burn the boats for the reason you mention. Without boats, you can't retreat.
SS