Streltsy (Russian: Стрельцы́, streltsý, literally "shooters"; sg. стреле́ц, streléts, "shooter", from strelyat', "to shoot") were the units of Russian guardsmen from the 16th to the early 18th centuries, armed with firearms. They are also collectively known as Marksman Troops (Стрелецкое Войско). These standing forces reinforced the mounted nobility militia (Поместное Войско, Pomestnoe vojsko or Landed Army) mobilized during wartime.
Read more about Streltsy: Origins and Organization, Uniforms and Equipment, Service Conditions, Military Tactics, Politics, Disbandment