Jack Lucas, of Carlson Gardens, Lutterworth, spent four decades excavating and writing about the Roman town of Tripontium on the A5.
And in 2004 the voluntary group won a national archaeological award for its efforts.
Mr Lucas had been housebound with a liver and heart condition since last December and died on March 28, leaving behind wife Marion, son Jonathon and daughter-in-law Lesley and granddaughters Rebecca and Melanie, who live in Rugby.
Mrs Lucas said: "He was a very kind man."
Born in Earl Shilton in 1921, Mr Lucas became a painter and decorator after leaving school, and his love of archaeology was kindled during wartime travels of the Mediterranean and North Africa, where he worked as an aircraft fitter.
His love of historic remains never left him and he joined Rugby Archaeology Society in 1966, spending most weekends directing excavations at the former gravel pit and Tripontium site, which was occupied from the Roman invasion in 47AD to the fifth century.
The society received the prestigious Pitt Rivers award in 2004 at the British Archaeological Awards in Belfast, and Mr Lucas was elected a Fellow of the Society of Antiquities in London in 1992 for his meticulous work and detailed reports.
Society secretary and close friend Irene Glendenning said his excavation methods, which uncovered a complex bathhouse and gave valuable insights into pre-Roman Britain, have re-written the history books.
One of his discoveries was an ancient tile with the name of a native Leicestershire tribe, the Corieltauvi, inscribed on it by Tripontium's literate inhabitants.
An Oxford academic wrote extensively about the tile, which was pieced together over several years, because Mr Lucas never let anything be thrown away lest it revealed archaeological secrets.
Mrs Glendenning said: "That's why we can say that to this date the work he has done has changed history.
"His work will be recognised in years to come. The fact that he did this work for nothing, as a volunteer, makes it extremely important."
Mr Lucas did not just catalogue archaeological findings, he also wrote an extensive war diary which was last year transcribed on a BBC website about the Second World War.
An excerpt from 1943 records an encounter with an old school teacher in Italy and reveals his love of the country, which grew into a passion for Roman history.
He said: "We are billeted in the school town and in the evening of November 6 I had a surprise, a visit from my old school teacher Jackie Birch from Hinckley. He is sergeant in the wings signals at Foggia.
"He gave me a bottle of whisky. He brought back a lot of memories. On my last visit to Bari I sat with a girl in the cinema when the ceiling fell on us.
"Jerry had sneak bombed the port and hit two ships full of ammunition. The town had to be evacuated quickly as mustard gas was rumoured to be on the ships. This was confirmed later.
"December 9 up at 4am and on to a boat at 4pm in Taranto docks, arrivederci beautiful Italy."
Mr Lucas's funeral was held at St Mary's Church in Lutterworth on Tuesday, April 4, and he was buried in the church cemetery.