Always loyal to the British Crown, the men were unpaid volunteers whose wish was to defend the Island of Guernsey from foreign invaders.

The commander of all military forces in Guernsey has always been appointed by the Crown, originally Wardens or Keepers, sometimes using the title Captain or Governor.

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

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

[2] A Henry III survey dated 1248 records that Islanders were free from (overseas) military service, excepting assisting the Duke of Normandy to recover England if necessary.

[1][5]: 13  The militias of Guernsey, Jersey, Alderney and Sark can claim to date from 1337, making them the oldest regiments of the British Army.

The Militia men from St Martin's and the Forest parishes met the French at Les Hubits and won the battle.

[10] Training was undertaken weekly in each parish, using common land, or at a specialist place near each church named Les Buttes where archery could be practiced.

[11] In 1372 Owain Lawgoch a claimant to the Welsh throne, at the head of a free company, on behalf of France, attacked Guernsey, popularly called "La Descente des Aragousais".

Owain Lawgoch withdrew after killing 400 of the Island militia,[12] when ordered by Charles V to sail to La Rochelle.

There is a report that the French were put off landing on Alderney by the sight of a mass of red coats in a watch post, these being women.

Whilst there he recovered the Crown of England that had belonged to Charles I from the cupola on top of the Court House in Jersey and brought it back to Guernsey, delivering it to the Governor of Castle Cornet.

[15] It was only on 17 December 1651, after an 8-year siege, regular bombardments and half-hearted attacks, including one in March 1651 by the militia, where 30 were killed, that the castle capitulated, the last Royalist garrison to surrender.

[18] Guernsey passed an ordinance requiring the militia men to wear uniforms in 1780, paid for by each man if they could afford it, otherwise by the parish.

The rebels had, during their period in charge, continued to mount guards and undertake the normal routine of the fort despite the lack of officers.

[3]: 11  In 1795 one soldier on sentry duty at Hougue à la Pierre battery, Belle Grave Bay, was caught insisting civilians provide him with the military password or pay a fee if they wanted to pass by.

The militia being considered as the first line of defence against the expected French invasion and were constantly exercising and called out for guard and watch duties.

[3]: 13 Defences were strengthened, over 60 gun emplacements and ammunition magazines were built to defend possible landing beaches,[23] manned by the militia artillery regiment.

With the draining of the Braye du Valle by 1808, new military roads were built, the "Route Militaire" along the Braye du Valle to the Vale Church, with other roads improved to military standard, from St Peter Port to Fort Hommet and from St Peter Port via St. Martin to the Forest where it split with one branch going to Torteval, the other to Fort Grey.

Uniforms for the three regiments continued with differing facings, North was Green, the West had Black and the South Blue.

[26] A detachment of the Royal Guernsey Militia attended the 1897 Diamond Jubilee of Queen Victoria as well as competing at Bisley.

[31] In 1901 it was reported that any man in Guernsey, when called upon, was bound by law to attend with pay 21 days of training with the Militia until he was declared efficient.

This training took place during the month of August, and any man failing to make the grade had to return the following year until he qualified.

[35] Reinstated after World War I in 1922, the militia was scaled back in 1929, following a reduction in funding, to a small volunteer force.

[36] One former member of the militia, Lt. Hubert Nicholle who had travelled to England in 1939 to join the Hampshire Regiment agreed to travel back to Guernsey by the British submarine H43 where on 7 July 1940 he undertook a successful reconnaissance of German defences in the Island during the lead up to Operation Ambassador, before being picked up on 10 July.

[37] Undertaking a second landing with fellow Guernseyman Lt. James Symes on 3 September 1940, in civilian clothing, the pickup arrangements failed and the two were forced to surrender, after having obtained help from Ambrose Sherwill to get Guernsey Militia uniforms, being treated as POWs rather than shot as spies.

In February 1925, in accordance with General Order No 5034 The London Gazette published a complete list of Battle Honours awarded for the Great War.