IRA's blueprint for bombs during Ireland's War of Independence

An excerpt from They Put the Flag a-Flyin' The Roscommon Volunteers by Kathleen Hegarty Thorne

How was the poorly-equipped IRA supposed to fight against the mighty British army without sufficient guns? Steal them, of course! There were plenty within the confines of barracks walls. But how to get in there?

The construction of the bombs used in the war was not an exact science. The maker had to guess as to the amounts of explosives to be used and oftentimes had to improvise a container. There was a general formula, but frequently the builder had to approximate or sometimes substitute. Different bombs were built in various ways depending on their projected use.

Cement mines were formed in one and a half foot square cases of wood. The cement was mixed with sand, but the heart was left empty so as to contain varying amounts of gelignite. It was capped with pitch overhead. The fuse went down through the middle of the frame. An electric detonator could also ignite it, thus giving the Volunteer a choice of utilising battery or fuse. Some of these mines could weigh as much as six stones.[i] Horse cart box bombs could weigh in at 10-11 lbs. while an ass cart box was built on a smaller scale.

Another method of construction included using a few sticks of gelignite, about four in all, loosely packed. The outside circumference was clamped with bolts. There was a screw through a hole to permit the entry of the fuse. Gelignite in this type of bomb was very sensitive. It could quickly get frozen in 4-5 hours of exposure to the cold.[ii]

When Volunteers travelled to Dublin, Diarmuid O'Hegarty would lecture them on use and construction of explosives. Classes would include hands-on experience in throwing bottle bombs, mixing and hardening explosive substances, use of gelignite in land mines, and use of explosive mines against doorways, passageways, and stone walls.[iii]

The Roche cottage of Ballinameen, near Boyle in County Roscommon, was home to many bomb-making sessions. Jack and Michael, both blacksmiths, constructed the devices with the assistance of their mother, Celia. The explosive mechanism used at the Elphin Barracks attack was constructed by John Murray, the Roche brothers, John Kelly, and Brian Connor at the Muckinagh munitions cottage.[iv] Four electric detonators and a coil of fuse had been procured by Jack Glancy in Dublin. He had wired Feely's Monument Company in Boyle that "the Marble was on the way." Feely had contacted Jim Dorr and several other Volunteers who waited at Drumsna Station for the contraband. These devices were somewhat successful in blowing gaping holes in the barracks wall. The bomb scheduled to have been used in the attack on the barracks at Ballaghaderreen in February 1920 was composed of a barrel of concrete reinforced with scrap iron, and weighed at least a stone.

It took the wiles of savvy commanders in the field, keen-witted intelligence men, and bold bomb makers to make the governance of Ireland so difficult and costly that the British finally abandoned their efforts and signed a treaty in 1921.

^{[i] Interview Jim Fehily, Ernie O'Malley notebooks, UCD Archives #131.}

^{[ii] Interview Bill O'Doherty, Ernie O'Malley notebooks, UCD Archives #131, p. 39.}

^{[iii] Interview Gerald Davis, Ernie O'Malley notebooks, UCD Archives #137.}

^{[iv] Interview John Kelly, Ernie O'Malley notebooks, UCD Archives #131.}

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