Yeomanry are part of the reserve for the British Army. At the start of First World War there were fifty-four yeomanry regiments in the British Army. Soon after the declaration of war, it was decided to increase the number of these volunteer mounted regiments. The new regiments were mirror formations of the existing first line regiments, with the same name and served initially in the same brigades. However they were all classed as second line units. The first line regiments, were numbered the 1/1st while the second line became the 2/1st (regimental name) or in cases where there were more regiments with the same name, or already numbered, the 2/2nd or 2/3rd.