Skull and crossbones variations have been used by several military forces. The "Jolly Roger", traditionally used by pirates, has been used by submarines.
Usage
Naval warfare
The Jolly Roger is the name given to any of various flags flown to identify a ship's crew as pirates. Since the decline of piracy, various military units have used the Jolly Roger, usually in skull-and-crossbones design, as a unit identification insignia or a victory flag to ascribe to themselves the proverbial ferocity and toughness of pirates.
Admiral Sir Arthur Wilson VC, the Controller of the Royal Navy, summed up the opinion of the many in the Admiralty at the time when in 1901 he said submarines were "underhand, unfair, and damned un-English. ... treat all submarines as pirates in wartime ... and hang all crews." In response, Lieutenant Commander (later Admiral Sir) Max Horton first flew the Jolly Roger on return to port after sinking the German cruiser and the destroyer in 1914 while in command of the E-class submarine .
In World War II it became common practice for the submarines of the Royal Navy to fly the Jolly Roger on completion of a successful combat mission where some action had taken place, but as an indicator of bravado and stealth rather than of lawlessness. The Jolly Roger is now the emblem of the Royal Navy Submarine Service.
Three distinct U.S. Naval Aviation squadrons have used the name and insignia of the Jolly Roger: VF-61 (originally VF-17), VF-84, and VFA-103. While these are distinctly different squadrons that have no lineal linkage, they all share the same "Jolly Roger" name, the skull and crossbones insignia and traditions. The first incarnation of the "Jolly Rogers" was established on 1 January 1943 at NAS Norfolk, as VF-17, flying the F4U Corsair. Inspired by the piratical theme of the aircraft's name, VF-17's commanding officer Tommy Blackburn selected the Jolly Roger as the squadron's insignia. The current squadron to hold the name is the VFA-103, Strike Fighter Squadron 103 (the "Jolly Rogers"), the skull and crossbones on all-black tails makes them easily identifiable.
The United States Marine Corps Reconnaissance Battalions use skull and crossbones on their emblems, and so do several aviation squadrons in the Air Force, Navy and Marine Corps.
Land warfare
Hussars, lancers and dragoons became established types of military units, with their typical uniform patterns (and weapons and tactics) maintained in many armies. In Chile, during the independence battles, a paramilitary guerrilla group against the royal Spanish army composed mainly by bandits and civilians, called Los húsares de la muerte (The Death Hussars) wore a Skull with two crossed femurs on the neck of their jackets.
In the Estonian War of Independence the skull and crossbones were symbols of Kuperjanov's Partisan Battalion. The badge is still used in the Estonian Army by the Kuperjanov Battalion, for example 2007 in Iraq.
Though not employing a black uniform, the skull and crossbones has been used by a succession of lancer regiments in the British Army. This origin dates back to the 17th Light Dragoons, a unit raised in 1759 following General Wolfe's death at Quebec, with an emblem of a death's head and the motto 'Or Glory' in commemoration of him. It was later used by the 17th/21st Lancers, the Queen's Royal Lancers, and now the Royal Lancers, who use the skull and crossbones as their Motto. They have also inherited the nickname of the 'Death or Glory Boys'.
In 1792, a regiment of Hussards de la Mort (Death Hussars) was formed during the French Revolution by the French National Assembly and were organized and named by Kellerman. The group of 200 volunteers were from wealthy families and their horses were supplied from the King's Stables. They were formed to defend against various other European states in the wake of the revolution. They participated in the Battle of Valmy and its members also participated in the Battle of Fleurus (1794). They had the following mottos: Vaincre ou mourir, La liberté ou la mort and Vivre libre ou mourir - Victory or death; Freedom or death; and Live free or die.
The 2nd Lancers Regiment of the Portuguese Army also use the skull and crossbones as symbol and "Death or Glory" as motto, as the regiment was raised by a former colonel of the British 17th Lancers.
During the Russian Civil War, the troops of the White Kornilov Division wore patches emblazoned with a skull and crossbones above a pair of crossed swords.