On 21 January 1919, Hogan and Dan Breen, together with Seán Treacy, Séamus Robinson and five other IRA members helped to ignite the conflict that was to become the Irish War of Independence. They shot dead two members of the Royal Irish Constabulary (RIC) - Constables McDonell and O’Connell - at Soloheadbeg in County Tipperary. The RIC men were transporting gelignite explosives, when they refused to surrender them, the IRA shot them dead. Robinson was the organiser of the action, while Treacy was the logistics expert.
"On the eventful day Dwyer saw the explosives, 160 pounds of gelignite, being loaded on a cart and heading off with a guard of two policemen. He cycled ahead and watched as they took the long route to the Soloheadbeg quarry. He took the short route and informed the anxious Volunteers of the convoy's size and movements. The horse was being led by two workmen, Edward Godfrey and Patrick Flynn, while the two policemen, Constables Patrick McDonnell and James O'Connell, walked behind with their rifles slung over their shoulders. As they passed Cranitch's Field near the quarry the policemen were called on to surrender by masked men. When they took up firing positions Seán Treacy, followed by Breen and Robinson, opened fire."
After Hogan was arrested on 12 May 1919 three of the other men who were part of the Soloheadbeg ambush ( Dan Breen, Seán Treacy and Séamus Robinson) were joined by five men from IRA East Limerick Brigade in order to organise Hogan's rescue. Hogan was being transported by train to Cork on 13 May 1919, and the men, led by Treacy, boarded the train in Knocklong. A close-range shoot-out followed on the train. Treacy and Breen were seriously wounded in the gun fight, two policemen died, but Hogan was rescued. He was spirited away to Knocklong village where his handcuffs were cleaved by Séan Lynch, one of the rescuers, in the local butcher's shop.
Hogan took no part in the Civil War. He went back to farming in Donohill but sold the farm some time afterwards, he then bought a vegetable farm in County Dublin but this venture did not succeed. He married Christina Butler and had three sons; Hugh, Thomas and Sean. In later years he was in poor circumstances, he lived on his own in North Great George's Street, Dublin. Due to illness in his later years his memory was not quite so clear and his handwriting was almost illegible. He was also very disillusioned with the way the Irish people had developed their country from the time the Republic of Ireland gained freedom. Hogan stayed with Seamus Robinson and his family in their house on Highfield Road close to his death. He died aged sixty-seven on Christmas Eve 1968. His death was reported RTÉ. He is buried in the family grave in Tipperary town.
- Brendan A. Creaner. "The Rescue at Knocklong". Knocklong-Rescue.com. Retrieved 8 December 2006.
- Jim Maher (1988). The Flying Column - West Kilkenny 1916-1921. Geography Publications.