Online for the first time and exclusively through Find My Past is the Militia Service 1806-1915 Collection.
I've had a breeze through the collection and was surprised (for no real reason) to identify seven of my Cork ancestors. In all but one case, there were four pages of details available to view.
By way of example, here are the details gleaned from one set of papers: Patrick Santry was born in Buttevant but had been living in Ballyhea, north county Cork, for at least a year when he joined the Royal Artillery on 28 March 1896. Aged 27 years and one month, he was a labourer working for Mr W Buckley of Charlesville. He was 5ft 10½" tall, weighed 132lbs, had grey eyes and brown hair, and a tattoo (possibly the initials 'L D') on his right forearm. He was Roman Catholic, and had quite a neat signature.
Patrick held the rank of gunner until he had completed his initial training and was promoted to the rank of Corporal on 1st June 1896. He turned up for training in 1897 and moved into the Militia Reserve on 23rd July 1897. The final entry appears to read 'Deserted 6 July 1898'.
As you can see, these papers provide rich details and colour that won't often be found in other records (some of the later records even include photographs of the soldier), so they are a very valuable addition to the Irish genealogy resource portfolio.