[2] Following the outbreak of violence in Northern Ireland in 1969, known as The Troubles, the Irish Government sent soldiers to the border area.

The flash symbolism is based on the Irish mythological warrior Cúchulainn, given the relevance to the battalions area of operations and headquarters.

The 27th Infantry Battalion celebrated 40 years since its establishment with a parade in Dundalk town on 31 August 2013.

Throughout the troubles, the 27th Infantry Battalion's largest commitment was providing checkpoints on border crossings in support to the Garda Síochána.

In 1979 the battalion provided security at Killineer near Drogheda during Pope John Paul II visit to Ireland.

In 2015 soldiers from the battalion assisted Gardaí searching for Dundalk teenager Ciara Breen who went missing from her home in 1997.

In 1978 and again in 1987 the battalion provided an emergency firefighting service when Dundalk Fire Brigade went on strike.