[1] One of the regiments formed was the Prince of Wales's Own Donegal Militia, based at Lifford, which saw action during the Irish Rebellion of 1798.

Their role was to man coastal defences and fortifications, relieving the Royal Artillery (RA) for active service.

[2][3][4][9][10][11][12] The Donegal Artillery Militia was embodied for duty in September 1855 during the Crimean War when the bulk of the Regular Army was away.

Each militia unit had a large cadre of permanent staff (26 in the case of the Donegal Artillery) and a number of the officers were former Regulars.

[4][11][19] From April to September the brigade's duties consisted of escorting 1000 Boer prisoners of war by sea to St Helena, and on return to South Africa they assisted in manning the defences of Cape Town and Simonstown.

While there, they took part in demolishing 32 miles (51 km) of railway lines to the north and laying land mines in the kopjes adjoining Zoutpans Drift.

[4][11][19] In November the remainder of the Donegal company under Maj Reed (promoted to Lt-Col on 12 October) moved from Cape Town to Kimberley, where they were broken up into small detachments manning field guns at various posts, including manning a gun on one of the armoured trains running out of Kimberley.

Milligan and 28 ORs of the Donegals joined a relief column for Schweizer-Reneke, which involved a three-day march, fighting all the way.

Lieutenant-Col Reed became OC Troops at various places, including 'A' Section of the Kimberley defences in February 1901, and was Commander, Royal Artillery, to Major-General Pretyman, Military Governor of Orange Free State, on 2 April.

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.

[22][23] 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.

The following served as Honorary Colonel of the unit:[15] On formation the corps adopted the blue uniform and red facings of the Royal Artillery.

The officers wore the standard North Irish Division helmet plate with 'DONEGAL ARTILLERY' on the lower scroll.