Pacifists have condemned a decision to honour veterans of Bomber Command with a permanent memorial.
More than 55,000 men from Bomber Command lost their lives
The Peace Pledge Union has said that commemorating the deaths of large numbers of people was not appropriate in the modern age.
A stone, carved by stonemasons at Lincoln Cathedral, will be dedicated to Bomber Command at a ceremony on Sunday.
Veterans campaigned for 60 years to mark the deaths of 55,000 RAF men during World War II bombing campaigns.
Albert Beale, from the Peace Pledge Union, said: "I think the idea of commemorating, almost in a celebratory way, the killing of large numbers of people is really not appropriate in the modern day and age."
He said aerial bombing was a controversial topic during WWII.
"It wasn't only pacifists that found it controversial, there was great debate in public at the time.
"I think part of this commemoration is almost distinguishing between good bombs and bad bombs.
He added: "To try and validate the horrors that happened there is almost going backwards. It shows that humankind hasn't really learned from its own history."
One of the most controversial campaigns by Allied Forces was the bombing of Dresden in 1945, which resulted in 25,000 to 40,000 deaths in the city.
Former RAF navigator from 100 Squadron, 90-year-old Douglas Hudson, who is taking part in the dedication ceremony, said earlier that the memorial was long overdue.
"There has been no public recognition of Bomber Command and we have even been branded criminals by some people.
"I would invite anyone who feels like that to get into a confined space in a bomber then have the doors close on a flight that's five, six or seven hours long while people constantly try to bring you down.
"I think it's so important to have this memorial, as Lincolnshire was renowned during the war as Bomber County, so it is long overdue," Mr Hudson said.