Among the locations hosting centenary events last night was Carrickfergus, where many gathered at the ramparts to the town’s 12th century castle for a remembrance service.
Before that, there had been a short march to the town’s nearby Cenotaph for a wreath-laying ceremony.
The setting was quite apt, said 54-year-old organiser George Watson, since the area had played a pivotal role in defending Belfast Lough against potential German incursions.
He said: “Carrickfergus, like every town in the country, had people who went out to fight and died. The castle was used to store armaments, and four miles up the road at Kilroot was an artillery base to protect the lough.”
At around 11pm, the Cenotaph was illuminated in red, mirroring the blood-coloured poppies synonymous with the war.
Mr Watson said the intention is to keep the red lighting until at least November.
Meanwhile, Knockagh Monument, a towering stone obelisk which overlooks the east Antrim area, was bathed in red light for an hour from 10pm.
In Lisburn’s Thiepval Barracks, which are themselves named after a World War One battle, there was a ceremony with an estimated 220 troops from 38 Irish Brigade, 2 Rifles, 2 Royal Irish, as well as some from Royal Naval reserve base HMS Hibernia.
The ceremony may have been particularly affecting for members of 2 Rifles, based at Thiepval, since it came just three days after the fatal crash which killed soldiers Lance Corporal David Gwilt and Rifleman Dale Harris in the Cullybackey area.
Rev Michael Fava, senior chaplain, said it had been a “poignant” ceremony, allowing them the time to pause and reflect on the sacrifice of generations past.