Gunners Joseph Rowbottom, 27, from Wrawby, North Lincolnshire, and Albert Venus, 22, from Hull, died on 24 May 1915 during the Second Battle of Ypres.
Their remains were found during work on a new housing estate.
Relatives attended Ypres Town Cemetery where their bodies were reinterred, in coffins draped with the union jack.
The soldiers' remains, with shoulder titles from the North and East Riding Batteries of the RFA, were uncovered in the town in April 2013.
Ministry of Defence (MoD) researchers were only able to identify the two men of the six found.
Gunner Venus's great nephew John Howden, 73, from Roos, East Yorkshire, was handed the folded union jack that had draped his coffin.
He said: "When they handed me the flag I had a lump in my throat and tears in my eyes and I did not think it would affect me that way.
"You are at a distance and all of a sudden you're involved and it's near, it's just emotional."
Mr Howden said he had not known about his great uncle until he got a letter from the MoD.
He said he was pleased the link was proved following a DNA test.
Caroline Rowbottom, Gunner Rowbottom's cousin's granddaughter, received the flag on behalf of his relations.
Mrs Rowbottom, from Brigg, North Lincolnshire, said it had been a shock when the family received an MoD letter.
"Up until that point we did not even know of his existence - we did not have him in the family tree, which is very sad.
"The ceremony itself was very moving and very well put together," she said.
The traditional five-gun salute did not take place due to the heightened security level in the country in the wake of last month's attacks in Brussels.
Gunner Rowbottom had been a milkman before the war and was nicknamed Milky Joe in the local newspapers.
Gunner Venus enlisted in the 2nd Northumbrian Brigade in December 1914 and joined the Hull Batteries to complete his training as a gunner.
Six British soldiers who fought in the First World War have been given military burials more than a century after they were killed in Belgium.