military sales (FMS) contract between the U.S. and Canada. The Canadian guns were first fired by "A" Battery, 1 RCHA, at CFB Shilo and then were deployed to Afghanistan in support of Operation Archer, and were put into service in the Canadian theatre of operations around Kandahar in early 2006. This marked the first use by any nation of the M777 in combat operations. Regular RCHA units, reinforced by volunteers from Reserve units, continued to support operations until Canada completed its combat mission in Afghanistan in March 2014. Since Afghanistan In June 2017, the Royal Canadian Artillery Band, one of only two Regular bands in the Canadian Army, provided musical support for a contingent of the 2nd Battalion, Princess Patricia's Canadian Light Infantry which provided the Queen's Guard at Buckingham Palace, St James's Palace and the Tower of London, as well as Windsor Castle. In October–November 2018, the Band again deployed to England to provide musical support for a contingent from the 3rd Battalion, The Royal Canadian Regiment, which provided the Queen's Guard. Units The Royal Regiment of Canadian Artillery is composed of both regular and reserve (militia) forces. The regular force component is composed of five units, four of which are front line operation units; of these, three are field artillery regiments while the fourth is a low level air defence unit. The fifth regular unit is the Royal Canadian Artillery School. Additionally, while the three field artillery regiments are on the RCA's order of battle, they are badged as regiments of the Royal Canadian Horse Artillery. Regulars Reserves Regiments Independent batteries Since spring 2005, 10th Field Regiment, 26th Field Regiment and 116th Independent Field Battery have been grouped together as 38 Canadian Brigade Group's (38 CBG) Artillery Tactical Group (ATG). Bands Current: Former: Supplementary Order of Battle Regiments on the Supplementary Order of Battle legally exist but have no personnel or materiel. Order of precedence RCHA on parade with guns: RCHA on dismounted parades: RCA units: Despite not being the senior component of the Canadian Army, the honour of "the right of the line" (precedence over other units), on an army parade, is held by the units of the RCHA when on parade with their guns. On dismounted parades, RCHA units take precedence over all other land force units except formed bodies of Officer Cadets of the Royal Military College of Canada representing their college. RCA units parade