A combined land and sea attack, usually associated with the capture of a beachhead or coastal area, is known as amphibious warfare. First attempted by the ancient Persians during the Battle of Marathon in 490 BC, successful coordination of amphibious assaults are considered to be among the most complex military operations. When ship-mounted guns were developed, naval vessels would open fire on ground forces and gun emplacements while merchant ships were used to land troops and supplies. The first modern amphibious assault took place at Gallipoli during World War I. Poorly planned and executed, this assault failed, but served as an example of the need for perfect coordination of forces in this type of attack. As battlefield communications improved, and the range of ship-mounted weapons incr