After the Easter Rising, Dickson remained in Dublin. Then, he says, a number of subalterns, including himself, a Second Lieutenant, received new orders:

"The court-martial at Richmond Barracks sentenced many of the rebels to imprisonment and a number of the leaders to death. One evening five subalterns were ordered to command firing parties to shoot five of them ... the following dawn. A kindly but strict old Major of one of the Battalions gave detailed instructions to each of us ..."

Dickson describes how arrangements were made in a way as to ensure "no man knew whether his rifle had been loaded with blank or with ball; each was thus left not knowing whether he personally had shot the man or not."

Dickson then details how events unfolded, with the men marching their squads "... long before dawn in a dismal drizzle, but the men with memories of our losses seemed to have no qualms as to doing the job: 'Pity to dirty all these rifles; why can't we do him in with a bit of bayonet practice?"

"We had to wait while it grew fairly light and I took the chance to instruct the squad exactly what orders they would get. I didn’t want any muddle about getting them back around that wall. 'After Ready', I told them, 'on the word 'Present'', you bring your rifles smartly up to the standing-arm position aiming at the piece of white paper pinned on his chest and on the word 'Fire' steady pressure on the trigger, just like on the range ..."

"Thanks to that preparation it was carried out smoothly. The thirteen rifles went off ... The rebel dropped to the ground like an empty sack ... They marched in perfect order round that wall, grounded arms ..." Dickson noted, "Remember, we had all lost some good pals, in our first day's active service."

Dickson says that afterwards: "I can't say I felt much except that it was just another job that had to be done; though I was glad there was no doubt the rifles had done their work and there was no need for me to do what that old Major had told me, about the officer going back and finishing the job off with his revolver."

Elsewhere, however, he would describe this duty as having been a hateful one.