Formed in 1337, the Royal Militia of the Island of Jersey can claim to be the oldest sub-unit of the British Army,[1] although, because it is not a regiment, and was disbanded for decades in the late 20th century, it is not the most senior.

A militia force was organised in accordance with the order on 24 July 1203 of King John to provide a "sufficiency of men and money to defend the Island from the enemy".

[2] In 1214 Eustace the Monk, a pirate, based in Sark arrived under orders from Philip II of France to harry the Channel Islands.

In Guernsey Eustace met a newly raised and locally armed defence force comprising the whole manhood of the Island.

[4] The following year, in response to the threat of a repeat of this incursion, King Edward III ordered Thomas de Ferrers, Warden of the Isles, to levy and equip a militia of "all men capable of bearing arms, and to form them into companies of thousands, hundreds and twenties, and to lead them well-armed and arrayed for the defence of the islands".

The militia was not strong enough to retake the castle and instead controlled half of the Island with their base in Grosnez Castle[9]: 55–6  where they stayed until 1468 when the invaders were expelled by a Yorkist English army led by Richard Harliston, supported by the militia commanded by the Seigneur of Saint Ouen and after a siege of Mont Orgueil that lasted 19 weeks.

[3] In 1545, the Jersey Militia consisted of 12 parochial bands, many of which were called into action in 1549 when a force of French pirates, who had captured Sark as a base for their activities landed at Bouley Bay, advancing inland they met the militia who defeated them and driving them back down to the beach, killing up to a thousand in pursuit.

[9]: 61–2  In 1555 Parish Companies were ordered to practice every Sunday, weather permitting, firing Arquebus, Bow and arrow and Crossbow.

[9]: 76–80  Outnumbered, the militia fell back, 340 retiring into Elizabeth Castle, where they had provisions for eight months, others to Mont Orgueil which was besieged first and following negotiations surrendered with 40 Royalists supporters, who wanted to continue the fight, being allowed to go to Elizabeth Castle,[11] which was then put under siege and after a week, a lucky shot hit a powder store which exploded, killing six, and burying 40 under rubble.

[11] The militia was reorganized and uniformed in scarlet by the Governor of Jersey, Sir Thomas Morgan, in 1678, and in 1685 a Troop of Horse was raised (which later became Dragoons).

[9]: 473 On 28 May 1778 the Governor of Jersey, Field Marshal Henry Seymour Conway, submitted plans to Lord Weymouth for the construction of 30 coastal towers to forestall, or at least impede French incursions on the island.

Four more Martello towers were built 1835 Lewis, 1834 Kempt, 1837 Victoria and La Collette to further improve Island defences.

A small number of the ringleaders were found guilty, spent a few days in the prison and were then treated to a meal out in the town by their comrades.

Other members of the Regiment served as guards at the Blanches Banques Prisoner of War Camp located at St Brélade.