While most of the Regular Army was fighting overseas, the coasts of England and Wales were defended by the embodied Militia, but Ireland had no equivalent force.

The new Act was based on existing English precedents, with the men conscripted by ballot to fill county quotas (paid substitutes were permitted) and the officers having to meet certain property qualifications.

[10] The French Revolutionary and Napoleonic Wars saw the British and Irish militia embodied for a whole generation, becoming regiments of full-time professional soldiers (though restricted to service in Britain or Ireland respectively), which the regular army increasingly saw as a prime source of recruits.

They served in coast defences, manned garrisons, guarded prisoners of war, and carried out internal security duties.

A large French expeditionary force appeared in Bantry Bay on 21 December and troops from all over Ireland were marched towards the threatened area.

[8][13][14] The expected Irish Rebellion finally broke out in May 1798, and during its suppression the Londonderry Militia operated in Counties Dublin, Wicklow, Kildare, Carlow and Wexford.

With the diminishing threat of invasion after 1799, the strength of the militia could be reduced, and the surplus men were encouraged to volunteer for regiments of the line.

[18] In July 1800 Lord Castlereagh, by now the Chief Secretary for Ireland, was promoted to Colonel of the Londonderry Militia, with Sir George Hill, 2nd Baronet as his lieutenant-colonel.

Over the following years the regiments carried out garrison duties at various towns across Ireland, attended summer training camps.They also provided volunteers to transfer to the Regular Army.

The following year Lord Castlereagh stated that no less that 42 recruiting parties crossed from England to Belfast, where the Londonderry Militia was stationed, to compete for 150 volunteers from his regiment.

By the end of July 34 out of 38 Irish militia regiments had volunteered for this service, including the Londonderry, which served in England in 1811–13.

[9][23] Another Act in November 1813, promoted by Lord Castlereagh, invited the militia to volunteer for limited foreign service, primarily for garrison duties in Europe.

[30][31][33] A Londonderry Artillery Militia was formed in January 1855, but it was always small, comprising a single company of just three officers, a surgeon, and 81 other ranks (ORs).

For the Donegal Militia this was in Sub-District No 64 (Counties of Londonderry, Donegal, Tyrone and Fermanagh in Belfast District of Irish Command:[39] Although often referred to as brigades, the sub-districts were purely administrative organisations, but in a continuation of the Cardwell Reforms a mobilisation scheme began to appear in the Army List from December 1875.

The Londonderry Militia was assigned to the Garrison Army manning a range of small forts and posts across Ireland.

Unlike the earlier Londonderry Artillery company, this was a substantial unit, with an established strength of 619 all ranks organised as six batteries.

There were moves to reform the Auxiliary Forces (Militia, Yeomanry and Volunteers) to take their place in the six Army Corps proposed by St John Brodrick as Secretary of State for War.

[42][43] Under the sweeping Haldane Reforms of 1908, the Militia was replaced by the Special Reserve, a semi-professional force whose role was to provide reinforcement drafts for Regular units serving overseas in wartime.

Lieutenant-Colonels included: The following served as Honorary Colonel: The uniform of the Londonderry Militia was a red coat with blue facings.

[9] The Londonderry Light Infantry wore yellow facings,[39] and the cap badge consisted of a simple bugle-horn suspended from a cord with a shamrock knot, surrounded by a garter inscribed 'LONDONDERRY REGIMENT', topped by a three-towered castle.

The officers wore the standard North Irish Division helmet plate and embroidered pouch, each with 'LONDONDERRY ARTILLERY' on the lower scroll.

[6][50] On the outbreak of the French Revolutionary War the English counties had drawn lots to determine the relative precedence of their militia regiments.