Although he was part of various companies, he began working full-time on his brother Joseph’s staff from 1915 and, having missed many drills, he left his battalion. During Holy week, 1916, Jack was kept busy doing jobs for Joe. Jack liaised with Liberty Hall and other locations around the city. During Easter week, Jack was a lieutenant with the GPO garrison. He recalled his positions in the GPO:
I
was on Joe's staff and was put in charge of a little section first on the
ground floor of the G.P.O. towards Prince's St. Then I had a little section on
the first floor in front. I knew very few of the people in the Post Office.
He
was sent to the National Volunteers headquarters on Parnell Square and returned
with arms and ammunition. Later in the week Jack took out a sniper on the roof
of the Imperial Hotel who was firing upon those trying to keep the fires of the
GPO under control.
Jack
evacuated the shelled remains of the post office:
I
was one of the latest to leave the P.O. because I was worried about a couple of
prisoners two British tommies, I think and I ran around the building to see if
they were still there. When I came up there was only one man left behind, an
officer whose name I do not remember and whose job it was to see that everybody
was evacuated.
After
the surrender, Jack was brought to the Rotunda, but he noted that he was not
near his brother Joseph and did not have the opportunity to speak with him
until they were both in Richmond Barracks on the Sunday, 20 April. Jack
recalled part of their conversations:
He
said very definitely that they were going to shoot him but would not shoot us.
He also said they would shoot the signatories to the proclamation. He was
worrying a lot about Tomás McDonagh.
Jack
was sentenced to death following the rising, but had this sentence commuted to
ten years’ penal servitude. After spending time in a variety of Irish and
English prisons—Richmond Barracks, Kilmainham, Mountjoy, Portland, Lewes,
Parkhurst, Pentonville—Jack was released in 1917. The team at The Belvederian must have received word
of Jack during his time in prison as they reported on him in the 1917 edition:
Jack Plunkett is still at Lewes Gaol undergoing his
term of imprisonment in connection with the Rebellion. He is in the best of
spirits.
During
the War of Independence, Jack was on the staff of Rory O’Connor, IRA Director
of Engineers. He took the anti-treaty side in the Civil War and fought with the
garrison that occupied the Four Courts, June 1922, and was later imprisoned.
Jack studied engineering at UCD for a time and, as a long-time member of the
IRA, used his knowledge and skills by specialising in production of explosive
devices and in radio transmission. Following a raid on an IRA wireless
broadcasting station, Jack was arrested, December, 1939. During his time
imprisoned at the Curragh, he went on a forty-day hunger strike and survived.
Jack
later lived at 51 Eglington Road, Donnybrook and was an electrical engineer
with the ESB for many years. He suffered from chronic depression. Jack Plunkett
died 27 August, 1960. He was buried in Glasnevin Cemetery.
