Originally from Ballyduff, County Waterford, Berry joined the army at the age of 18. Berry was a career Line Infantry officer and served for six years as the second-in-command of the Army Ranger Wing, Ireland's special operations unit, before qualifying as a medical doctor and becoming the head of the Military Medical School of the Irish Defence Forces. He deployed overseas five times, with NATO in Kosovo, the EU in Chad and the UN in the Middle East (Lebanon).[2]
Berry came to public attention in 2019, unusual for a soldier, particularly with service in the ARW, when upon retiring after 23 years in the Defence Forces, he spoke to the media about poor pay and conditions within the military and the disillusionment of military personnel with the perceived dysfunctional relationship between the military authorities and the Department of Defence.[3][4]
Berry holds a bachelor's degree in Science and Master of Law in Peace Support Operations and International Humanitarian Law from NUI Galway, a Bachelor of Medicine, Obstetrics and Surgery from the Royal College of Surgeons in Ireland as well as qualifications in French language, and leadership, management and defence studies from NUI Maynooth.