A Grenadier was originally a specialized assault trooper for Siege operations, first established as a distinct role in the early 17th century. Grenadiers were soldiers who would throw grenades and storm breaches, leading the forefront of such a breakthrough.
The earliest references to these grenade-throwing soldiers are from Austria and Spain. References also appear in England during the English Civil War. However, it was King Louis XIV of France who made the Grenadier an official type of soldier and company during his army reforms late in the 17th century. According to Rene Chartrand, Lt. Col. Jean Martinet introduced the idea of having men detailed to throw grenades in the Régiment du Roi in 1667.
The first grenades were small spheres filled with Gunpowder fused with a length of slow-match. The grenadiers had to be tall and strong enough to hurl the heavy objects far enough not to harm themselves or their comrades, and disciplined enough to stand at the forefront of the fight, light the fuse, wait, and throw at the appropriate moment to minimize the opportunity for the enemy to throw the grenade back. Over time, such regiments came to be regarded as elite.
Wide hats with broad brims were discarded and replaced with caps. By 1700, several regiments had adopted a cap in the shape of bishop's MITRE, usually decorated with the unit's insignia. In addition to grenades, they were equipped with contemporary longarms. The uniform included a belt tube that held the match for lighting the fuse; this feature was retained in several later grenadier uniforms.
Grenade usage declined significantly in the 18th century, a fact that can be attributed to the improved effectiveness of massive Infantry line tactics and firelock technology; however, the need for elite assault troops remained, and the existing grenadier units were used for this purpose. The term grenadier was retained or adopted by various elite infantry units, including Potsdam Grenadiers, Napoleon's Imperial Guard, the Imperial Russian Grenadier Leib Guards Regiment, Grenadier Guards and the 101st Grenadiers. The latter was part of the British Indian Army and claimed to be the first and oldest grenadier regiment in the British Empire.
In modern times, regiments using the name grenadiers are effectively indistinguishable from other infantry, especially when hand grenades, RPGs, and other types of explosive arms have become standard-issue weaponry; however, such regiments retain at least the tradition of their elite past. Grenadier can also refer to soldiers utilizing grenade launchers, including those mounted on rifles.
In the Swiss Army, the Grenadiers form the elite Special forces. They are used for especially challenging operations and are initially trained in Isone, a secluded, mountainous region in the South of Switzerland. The Swiss Grenadiers specialize in Urban warfare, guerilla warfare, anti-terrorist operations, Commando tactics, Sniper missions, and other special operations.