Vandals have destroyed six war graves at the Hirst Wood burial ground in Bradford in the lead-up to the D-Day anniversary.
Police said the gravestones for veterans of the First and Second World Wars were damaged on either Monday or Tuesday.
Julie Watson said the vandalism was “absolutely despicable, and left her feeling “disgusted”.
She said her uncle Peter William Bilsborough, a sergeant with the Royal Air Force Volunteer Reserve, was among those who had his gravestone damaged.
“It's horrible that the people that are responsible for this are able to walk around freely, but those who died cannot because they sacrificed everything for us,” she said.
“My uncle died before I was born, but he has been in my life because I have put the time in to researching him and finding out about what he did in the Second World War.”
She said Sergeant Bilsborough died in 1941 after the bomber he was flying in was forced to ditch in the ocean following engine failure.
The Hirst Wood Regeneration Group said it’s impossible to understand the “callous thoughtlessness” of those who damaged the graves.
On Facebook they said: “Do they boast to their friends and relations that they managed to smash gravestones?”
The Commonwealth War Graves Commission said the damaged graves will be returned to a state “befitting their sacrifice”.
“We are deeply upset that someone has shown such a complete lack of respect on the 75th anniversary of D-Day,” a spokesman said.
West Yorkshire Police detective inspector Amanda Middleton said police are looking for witnesses.
"The gravestones were destroyed in what was a mindless act of destruction and I would urge anyone with any information to come forward and speak to the police,” she said.
"High visibility reassurance patrols have been stepped up in the area whilst officers continue with their inquiries."