In warfare, ramming is a technique that was used in air, sea and land combat. The term originated from battering ram, a siege weapon used to bring down fortifications by hitting it with the force of the ram's momentum. Thus, in warfare ramming refers to hitting a target by running oneself into the target.
Today, hand-held battering rams are one tool among many used by law enforcement and military personnel for door breaching. Forcible entry by criminals has been implemented using such methods as vehicles rammed into buildings.
The ram was commonly used in antiquity, and was an important part of the armament of the galleys of Imperial Rome. The ancient Greeks used their trireme vessels for ramming as well. In ancient China, rams were largely unknown as the lack of a keel and the flat shape of the junk's bow was not conducive to the build of an elongated underwater spur.
The ram's first recorded use in modern times between major warships, however, was in the American Civil War, at the battle of Hampton Roads, when the armoured Confederate warship Virginia rammed the Union frigate Cumberland, sinking her almost immediately.
Another significant success of the ram in wartime was at the 1866 battle of Lissa, between Italy and Austria. The Italian ironclad Re d'Italia had been damaged aft by gunfire, and had no rudder. Lying helpless in the water, she was struck amidships by the Austrian Ferdinand Max, the flagship of the Austrian Commander-in-Chief Admiral Tegetthoff. The Austrian ship retreated unharmed as the Italian vessel rolled over and sank.
During World War I, HMS Dreadnought rammed and sunk German submarine U-29. This was an incidental use of the ship's bow, however. In 1918, the British luxury ocean liner RMS Olympic rammed SM U-103 in which the submarine sustained such heavy damage that its crew was forced to scuttle and abandon ship.
In World War II, naval ships often rammed other vessels, though this was often due to circumstances, as considerable damage could be caused to the attacking ship. The damage that lightly constructed destroyers took from the tactic led to it being officially discouraged by the Royal Navy from early 1943, after the HMS Hesperus was dry-docked for three months following sinking U-357 in December 1942 and HMS Harvester was torpedoed and sunk following damaging her propellers during the ramming of U-444 in March 1943. USS Buckley (DE-51) rammed U-66; and HMS Easton rammed U-458.
On 29 January 1943, the Japanese submarine I-1 was rammed and wrecked by the New Zealand naval trawlers, Kiwi and Moa in shallow water at Kamimbo Bay, Guadalcanal during Operation Ke. The submarine of 2,135 tons was much larger and more heavily armed than the minesweeping trawlers of 607 tons each.
On 5 November 1942, the Finnish submarine Vetehinen rammed the Soviet submarine Щ 305 in the Sea of Åland and sank it. Vetehinen was on a night patrol searching for Soviet submarines. A contact was found, and after confirmation of an enemy contact Vetehinen launched a torpedoes, which missed probably due being fired at too short distance. Vetehinen then opened fire with its deck guns. Deck guns managed to damage the Soviet submarine which by now had started an emergency dive. The Captain of Vetehinen, determined not to let the submarine escape ordered his submarine to ram the other vessel which at last was a success.
During anti-submarine action, ramming was an alternative if the destroyer was too close to the surfaced submarine for her main guns to fire into the water. The tactic was used by the famous British anti-submarine specialist, Captain Frederic John Walker from December 1941 to the end of the war.
Superannuated British destroyer HMS Campbeltown was disguised as a German ship for the purpose of ramming the lock gates of the U-boat base at St. Nazaire on 28 March 1942. A large explosive time bomb charge in the bow of the ship exploded the next day, putting the dock out of commission for five years.
PT-109 was rammed and crushed by a Japanese destroyer, though the incident was at night and the PT-boat was idling to avoid detection, making it doubtful the destroyer's actions were intentional.
In 1988, two US naval ships, destroyer Caron and cruiser Yorktown, were lightly rammed by Soviet Mirka II class light frigate (FFL 824) and Burevestnik class frigate Bezzavetny (FFG 811) inside contested Soviet territorial waters in the Black Sea, near the port of Foros. None of the ships involved suffered significant damage.
During the "Cod Wars" between Britain and Iceland, unarmed fishing trawlers found themselves opposed by Icelandic Coastguard vessels and converted trawlers. As well as Royal Navy coastguard vessels, Britain sent large, ocean-going tugs and lightships to protect them and there were numerous ramming incidents against both sides, sometimes with very serious consequences.
Air warfare 
Ramming in air combat is a last-ditch tactic that was used when all else had failed. The ramming pilot could use his entire aircraft as a ram or he could try to destroy the enemy's controls using the propeller or wing to chop into the enemy's tail or wing. Ramming took place when a pilot ran out of ammunition yet was still eager to destroy an enemy, or when his plane had already been damaged beyond saving. Most ramming occurred when the attacker's aircraft was economically, strategically or tactically less valuable than the enemy's, such as by pilots flying obsolescent aircraft against superior ones or by single-engine aircraft against multiple-engine bombers. Defenders rammed more often than invaders.
A ramming attack was not considered suicidal in the same manner as kamikaze attacks—the ramming pilot stands a chance of surviving, though it was very risky. Sometimes the ramming aircraft itself could survive to make a controlled landing, though most were lost due to combat damage or the pilot bailing out. Ramming was used in air warfare in the first half of the 20th century, in both World Wars and in the interwar period. In the jet age, as air combat speeds increased, ramming became obsolete—the probability of successfully executing (and surviving) a ramming attack approached impossibility.
Ground warfare 
During World War II, the tanks crews would sometimes use their own vehicles to run over enemy positions (personnel, artillery etc.) instead of firing upon it. This tactic was especially popularised in Soviet Union. Facing the German Tiger or Panther tanks, the crewmen of T-34 tanks, who lacked the firepower to break their thick armour, sometimes preferred to use the speed and manouverability of their tanks to drive straight into Germans, gambling that the impact will break the enemy's tracks and immobilize it. Moreover, the attack could end with jamming the Tiger's turret, either by blocking it with T-34's own body or by damaging the turret's drive, eliminating the risk to the remaining Soviet units. However there was a serious risk of being destroyed by German guns before reaching the enemy tanks. In addition, sometimes (especially if the T-34 ran into the enemy's back), the ramming would rupture a Tiger's or a Panther's fuel tank and cause a fire, destroying both vehicles.
Siege warfare 
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