The beginning of Operation Banner has been remembered this month with commemorations across the UK, marking 50 years since the Army was deployed to the streets of Northern Ireland.
We have been speaking to veterans who served there during the near-38 years of Op Banner, in the period which became known as 'The Troubles'.
The government sent in troops, believing it was the only way to restore peace.
Paul Young, who was in B Squadron, The Blues and Royals, was deployed in 1971.
He explained how he was on guard at all times and that personnel would be targeted with homemade car, incendiary, paint and acid bombs, as well as shootings, while their main fear was people trying to tip their vehicles over.
Civilians of both sides would be caught in the middle.
"I remember just sitting there at about two o'clock in the morning, just on call to be there, a presence. Getting a knock on the battle hatch on the side of my driver's ferret," Paul said.
"I opened the battle hatch very slowly and quietly, and there was this little old lady and she had a silver tray with her best bone china, with some sandwiches and some cakes.
"She was from the Catholic side and she said 'I wanted to give you guys something because I can't do it during the day and I have to be very careful doing it now because I could get into trouble'.
"She snuck away back into her wee terrace house and I thought that was one of the nicest things that you'd come across, but it just shows you that some of the people were scared to go against the IRA and other people that were literally controlling those areas."
Rob Hughes was just 19 years old when the patrol he was in command of was ambushed by the IRA.
Visiting Belfast this year was the first time he had been in the city since 1991, and his emotions upon being back were mixed.
He said it seemed logical not to come back immediately, after having been injured during an incident while on duty with 1st Battalion, The Royal Green Jackets.
"We were helicoptered out to an area near the border, I was near a road where I went to do a checkpoint," he said.
"I decided to move away from the area because we had been warned about the risk of a secondary device.
"As I moved away I came under a hail of automatic machine gunfire, and I was hit with the first burst.
"The first I knew was a blinding white flash in front of my eyes, and then an extremely sharp pain in my legs, and I sort of landed a significant distance from where I was hit on the floor.
"It was the Provisional IRA.
"There were three gunmen, there was a GPMG (General Purpose Machine Gun) and two AK47s. I was told that by police subsequently.
"They had 365 days a year to pick what they were going to do, when they were going to do it.
"When push came to shove, all they would do is turn round, run away and cross the border, knowing that we couldn't pursue them.
"I was told names, the very next day when I was in hospital, but unfortunately there were no arrests and it appears there was no real investigation into it either."
In Londonderry, where families say their loved ones were killed unlawfully by British troops on Bloody Sunday, former Chief of the General Staff General Mike Jackson's face can still be seen.
He says the deployment of British troops to Northern Ireland "could not have been avoided".
"For many of the families, I no doubt represented everything they loathed about being part of the United Kingdom, there's nothing I can do about that," the former Army chief says.
"I have given evidence on the Saville Inquiry, and in the Ballymurphy inquest, the fact that I finished up as [Chief of the General Staff] and all of that, I suspect gives those who are against me their reason to, as you put it, demonise."
John Ross, from Northern Ireland, served with 2nd and 3rd Battalion The Parachute Regiment. He said: "It was certainly the Belfast I remembered, I knew a lot of people, I certainly knew the area well, and 3 PARA had just moved from Armagh up into Belfast.
"I went on a lot of patrols with older guys because they didn't have to worry about knowing where they were - I knew exactly where we were at all times.
"You [nowadays] can go anywhere in Northern Ireland, drive on any road, anywhere.
"You certainly couldn't go into certain areas as a Parachute Regiment veteran.
"I probably wouldn't come out alive."
For some politicians too, it has been a time for commemoration.
DUP leader, Arlene Foster MLA, said: "My father was shot during Operation Banner, at our home, so I'll be thinking about him today."
The DUP's Sir Jeffrey Donaldson MP, is an Ulster Defence Regiment veteran.
"I hope that they see that their sacrifice and their service has helped contribute to the Northern Ireland that we have today," he said.