In 1821, the army first adopted the “bell crown” cap as standard head gear for rifle and artillery soldiers. Like its predecessor, the “yeoman cap,” this features a top which is wider than its base, but with the addition of distinctly concave sides. This style of head wear had become popular in European armies–first with the Russians, then spreading throughout most of the continent. The 1821 Uniform Regulations stated that these were to be worn by company officers and enlisted soldiers. Soldiers were issued only one of these for a five year enlistment period, and as they were considered government property, were expected to return them upon completion of service.