The Northern Ireland Crown Forces Veterans for Justice group held a protest in support of Dennis Hutchings at Belfast City Hall on Monday.
It coincides with a similar event in Manchester.
Mr Hutchings (77) has been accused of killing a man in Co Tyrone over 40 years ago.
John Pat Cunningham (27), who had learning difficulties, was shot in the back as he ran away from an Army patrol near Benburb.
Mr Hutchings was told earlier this month that his trial will go ahead after the failure of his appeal, which claimed that the case was an abuse of process.
Mr Hutchings, from Cornwall, who suffers from kidney and heart disease, said that troops who served in Northern Ireland "were only there doing a job".
Calls for an amnesty relating to prosecutions on British Army veterans who operated in Northern Ireland have been rejected.
DUP East Belfast MP Gavin Robinson and NICFV spokesperson Wilfie Brown, who served with the Royal Irish for 22 years, spoke at the event.
Mr Brown said that around 150 people attended the event.
"All the prosecutions against soldiers are still active and it's a one way street," he said, "there are injustices at the heart of the judicial system. It's an absolute disgrace.
"We're not saying that people weren't shot in circumstances that could have been avoided.
"The army was the legitimate law force of this country and now we see the reward that terrorism pays.
"There are a lot of people walking around this town today who owe their gratitude to the crown forces so that they can now live in peace and they have been totally forgot about."