Burn one’s boats/bridges

Whether boats or bridges are burnt, the expression has been used figuratively only since the 19th century in the sense of staking everything on going forward to success because ruin and disaster is the only option. In a literal sense, however, the military practice of burning boats or bridges so that there can be no question of retreat seems to be very old. Roman generals certainly burned bridges behind them, preferring to cut off avenues of retreat in order to ensure victory. Muslim invaders of Spain in 711 burned their boats on the shore to ensure their troops would advance into the Iberian Peninsula. Cortes did the same thing to ensure success for his invasion of Mexico in 1519, although he did not actually burn his ships, rendering them unseaworthy instead.