Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A pontoon bridge or floating bridge is a bridge that floats on water, supported by barge-or-boat-like pontoons to support the bridge deck and its dynamic loads. While pontoon bridges are usually temporary structures, some are used for long periods of time. Permanent floating bridges are useful for sheltered water-crossings where it is not considered economically feasible to suspend a bridge from anchored piers. Such bridges can require a section that is elevated, or can be raised or removed, to allow ships to pass. Pontoon bridges are especially useful in wartime as river crossings. Such bridges are usually temporary, and are sometimes destroyed after crossing (to keep the enemy from using them), or collapsed and carried (if on a long march). They were used to great advantage in many battles throughout time, including the Battle of Garigliano, the Battle of Oudenarde, and many others. Pontoon bridges have been in use since ancient times.