A Musketeer was an Early Modern infantry unit equipped with a Musket. From 1368 the musket was used in the Ming Dynasty (maybe earlier), from the 1440s in the Ottoman Empire, 1520s in Spain, and 1545 in Japan and the Kingdom of Russia. Musketeers were the backbone of European armies from the 1600s until 1855, when rifles replaced muskets as the main infantry firearm.