In 1917 trooper Alfred Johnson was part of the 800 light horsemen to participate in the last ever successful mounted charge in times of war, the light horse charge at Beersheba Palestine on October 31 in 1917.
Upon the capture of the town, the British allied forces raised the union jack flag at the Beersheba post office.
"My grandfather, trooper Alfred Johnson who charged that day, thought it would look good hanging from his parents pub in Victoria, so that night it turned up in his saddle bags," Alfred's grandson Gary Johnson said.
Mr Johnson has now made the tough decision to hand over his grandfather's historic flag to the Australian War Memorial.
As this year marks the 102nd anniversary of the last successful mounted charge in times of war, Mr Johnson thought the timing was just right.
Mr Johnson said the flag had stayed in the family since 1917, getting passed down through the generations.
According to Mr Johnson the flag will be on display with a picture of his grandfather and the story of Beersheeba Day.
"I never thought of selling it because I don't want it to leave Australia," Mr Johnson said.
"It is one of the most significant World War I relics in history, it's a piece of Australian history."
Mr Johnson grew up with stories about his grandfather and the charge, which is what inspired him to represent the Lighthorsemen.
"I used to lay a wreath in Sydney to honour the Lighthorsemen but now I would rather do it locally," he said.
"You find that in country areas like Lithgow that many people had relatives who would have been in the infantry or horsemen."
Mr Johnson said he thinks Anzac Day is a very important part of national history.
"It should never be forgotten, I am proud of what they did," he said.
"I am just doing my small part to keep their memory alive."