The RHA has acquitted itself with distinction in the great wars of two centuries, the Napoleonic Wars, the Indian Mutiny, the Crimean War, the Peninsular War, the Anglo-Zulu War, the Boer War, World War I and World War II. In 1859, the term "battalion" was replaced by "brigade". (This in turn was replaced by "regiment" in 1939.) The five Horse Artillery brigades consisted of two batteries each. Between 1899 and 1924, the Royal Artillery was divided, with the creation of the Royal Field Artillery which utilised horse for its medium-calibre guns. When the Territorial Force was created in 1908, artillery units of the old Volunteer Force were converted into foot, horse, and garrison batteries. There were 14 batteries of horse artillery, 12 of which belonged to the RHA, the remaining two being provided by the Honourable Artillery Company. Territorial batteries were of four guns each rather than the six guns of regular batteries. The principal weapon of Territorial RHA units was the Ordnance QF 15 pounder although the Ordnance BLC 15 pounder was issued to some second-line RHA units formed in 1914. At the outbreak of World War I the regular RHA comprised twenty-five batteries, eleven of those serving in India with the Indian Army. They were equipped with the Ordnance QF 13 pounder. In the 1920s, development of trucks and track vehicles brought an end to operational use of horses. By 1927, medium artillery was drawn by tractors instead of heavy draught horses. By 1937, nine field brigades had been mechanised as well as a brigade of RHA. The last battery to be mechanised was K Battery, in 1939. Today, the ceremonial King's Troop alone retains the panache of the mounted batteries. At the onset of World War II, recruits were instructed that "the role of the Royal Artilleryman is, as it has ever been, to fight his gun, forgetful of self, to the last round in support of other arms." The following are current units of the Royal Horse Artillery:   The Royal Horse Artillery has provided the Queen's Guard on three occasions:  The King's Troop provides the Queen's Life Guard in Whitehall for three weeks in August each year while the Household Cavalry Mounted Regiment goes away for summer training. When on parade with its guns, the Royal Horse Artillery takes precedence over all.