On 1 July 1899, the Royal Artillery was divided into three groups: the Royal Horse Artillery and Royal Field Artillery comprised one group, while the Coastal Defence, Mountain, Siege and Heavy artillery were split off into another group named the Royal Garrison Artillery. The third group continued to be titled simply Royal Artillery, and was responsible for ammunition storage and supply. The RFA and RHA both dressed as mounted soldiers, whereas the RGA dressed like foot soldiers. The First World War brought with it a massive expanse of the Royal Artillery By 1917, there were 1,769 batteries in over 400 brigades totaling 548,000 men.
In 1920 the rank of Bombardier was instituted in the Royal Artillery. The three sections effectively functioned as separate corps. This arrangement lasted until 1924, when the three amalgamated once more to became one regiment. The Royal Horse Artillery, which has always had separate traditions, uniforms and insignia, still retains a separate identity within the regiment, however, and is considered (by its members at least) to be an élite.
Before the Second World War, Royal Artillery recruits were required to be at least 5 feet 4 inches tall and men in mechanised units had to be at least 5 feet 8 inches tall. In 1938, the Royal Artillery Brigades were renamed Regiments.