become increasingly vulnerable. Many armies started to use troops which could either fight on horseback or on foot as circumstances dictated. Fighting on horseback with swords and lances would allow rapid movement without cover from enemy fire, whilst fighting on foot with pistols and rifles allowed them to make use of cover and to form defensive lines. The first mounted infantry units were raised during the Mexican–American War (as the Regiment of Mounted Riflemen, but redesignated Third Cavalry Regiment in 1861), and others followed, for example in Australia in the 1880s. Terms such as "mounted rifles" or "Light Horse" were often used. The French Foreign Legion used mule-mounted companies from the 1880s. Each mule was shared by two legionnaires, who took turns in riding it. This arrangement allowed faster and more prolonged marches that could cover 60 miles in one day. In the Western Theater of the American Civil War, several infantry regiments were converted to mounted infantry and armed with repeating rifles. The Lightning Brigade at the Battle of Chickamauga was an example of these Union mounted infantry units. In the British Army, infantry units in some parts of the British Empire had a mounted platoon for scouting and skirmishing. In addition, many locally raised units such as the Ceylon Mounted Rifles, Cape Mounted Rifles, Natal Carbineers and Marshall's Horse fought as mounted infantry. In the Second Boer War, the British copied the Boers and raised large forces of their own mounted infantry. Among various ad hoc formations, the Imperial Yeomanry was raised from volunteers in Britain in 1900 and 1901. Many of the contingents from Australia, Canada and New Zealand (e.g. the Australian Light Horse and the Canadian Mounted Rifles) were MI (mounted infantry), as well as locally raised irregulars like the Imperial Light Horse and South African Light Horse. As artillery was of limited use against scattered Boer guerrilla bands later in the war, the mounted personnel of Royal Artillery units were formed into Royal Artillery Mounted Rifles. As part of the lessons learned from that war, British regular cavalry regiments were armed with the same rifle as the infantry and became well-trained in dismounted tactics. A version of the standard infantry rifle, the shorter-barreled LEC or "Lee-Enfield Cavalry Carbine Mark I" had been introduced in 1896. 20th century transition Many European armies also used bicycle infantry in a similar way that mounted infantry used horses. However