Canberra's Kate MacInnes to lead the Legacy Centenary Torch Relay on Monday

His wife Lauren and children Mark, then just 13, and Kate, only 12, were bereft.

Legacy Australia, which has been supporting veterans' families since 1923, very quickly came in to help Lauren, Kate and Mark.

"I just remember coming home and a Legatee being there and having a conversation with mum about what her next steps would be, about Legacy and about the community Legacy is, especially in Canberra," Kate, now 25, said.

"And the older I've gotten, the more my connection with Legacy, I think, has grown as well. Because when you're 12 and that happens, you don't really understand why somebody is trying to tell you about a charity and how they can help, because you're still trying to process everything else.

"But the older I've become and the more aware I am about what Legacy has done and can help children now going through the same thing, I have more of an appreciation of what they do. And I want to play a part in that as well."

Legacy grew from the ashes of World War I, with 60,000 Australian service personnel killed and more than 150,000 wounded, many dying soon after.

Returning soldiers formed the first Legacy clubs in 1923, keeping a promise to their dead or injured mates that their families would always be looked after.

Originally, it was returned servicemen who took on the duty of supporting widows and children. They later became known as Legatees, who continue that work today, whether it's helping to organise financial support or just calling in for a cup of tea.

Canberra Legacy, alone, supports more than 800 members of veteran families in Canberra, Yass and Boorowa, including covering medical expenses and the basics such as heating bills.

There are 32 children now supported by Canberra Legacy and they receive all kinds of of help, from assistance with school excursions to help to get their driver's licence.

Monday is a big day for Legacy in Canberra. It's the start of Legacy Week but also the running of the local leg of the Legacy Centenary Torch Relay, which has been travelling the world, highlighting the charity's work.

In Canberra, Kate MacInnes will be the first torch bearer as it leaves the Australian War Memorial at 10.30am on Monday.

"It's such an honour to be the first torch bearer," she said. "Especially because Canberra Legacy has given me so much."

Now an executive assistant for a deputy secretary in the federal public service, Kate said Legacy helped her to access grants and accommodation when she completed a business degree in Sydney. It also helped her with social activities when she was at school, connecting to other Legacy youth and helping to her attend a commemorative trip to Pozieres, France.

As a young adult, she felt guilty leaving her family behind to study interstate and was worried "something might happen", but Legacy was always there to check in on her mum at their home in Fadden and give Kate some peace of mind.

"It was just like having an extra person in the family to rely on, really," she said.

Kate has been told her dad was the ultimate "soldier's soldier".

She remembers him as a wonderful, hands-on parent, who coached her soccer team and didn't mind being silly and having fun.

Kate says does expect to feel her dad by her side as she strides out with the Legacy torch from the Australian War Memorial on Monday.

"I feel him with me all the time, but especially around Legacy Week," she said.

"You feel that little but more sentimental or connected during Legacy Week or on Anzac Day.

"I definitely think he will be there and mum always tells me he would be very proud I'm trying to keep alive his legacy, as well, because it's not something he would expect that I would do, but it is something he would be so proud I was doing."