Amphibious warfare is a type of offensive military operation that today uses naval ships to project ground and air power onto a hostile or potentially hostile shore at a designated landing beach. Through history the operations were conducted using ship's boats as the primary method of delivering troops to shore. Since the Gallipoli Campaign, specialised watercraft were increasingly designed for landing troops, material and vehicles, including by landing craft and for insertion of commandos, by fast patrol boats, zodiacs (rigid inflatable boats) and from mini-submersibles. The term amphibious first emerged in the United Kingdom and the United States during the 1930s with introduction of vehicles such as Vickers-Carden-Loyd Light Amphibious Tank or the Landing Vehicle Tracked. Amphibious warfare includes operations defined by their type, purpose, scale and means of execution. In the British Empire at the time these were called combined operations which were defined as "...operations where naval, military or air forces in any combination are co-operating with each other, working independently under their respective commanders, but with a common strategic object." All armed forces that employ troops with special training and equipment for conducting landings from naval vessels to shore agree to this definition. Since the 20th century an amphibious landing of troops on a beachhead is acknowledged as the most complex of all military maneuvers. The undertaking requires an intricate coordination of numerous military specialties, including air power, naval gunfire, naval transport, logistical planning, specialized equipment, land warfare, tactics, and extensive training in the nuances of this maneuver for all personnel involved. In essence, amphibious operations consist of the phases of strategic planning and preparation, operational transit to the intended theatre of operations, pre-landing rehearsal and disembarkation, troop landings, beachhead consolidation and conducting inland ground and air operations. Historically, within the scope of these phases a vital part of success was often based on the military logistics, naval gunfire and close air support. Another factor is the variety and quantity of specialised vehicles and equipment used by the landing force that are designed for the specific needs of this type of operation. Amphibious operations can be classified as tactical or operational raids such as the Dieppe Raid, operational landings in support of a larger land strategy such as the Kerch–Eltigen Operation, and a strategic opening of a new Theatre of Operations, for example the Operation Avalanche. The purpose of amphibious operations is usually offensive, except in cases