Forgotten Veterans UK has spent this week at Manor Nursery and Infant School in Inverness Road, Fratton, as part of the school's garden oasis project.
It's a scheme looking to transform the school into a wildlife-rich environment, teeming with life and taking the fight to air pollution.
The veterans worked alongside the children and volunteers from the Royal Navy to get the garden off the ground.
Acting deputy headteacher, Grace Brown, said: 'We raised £6,000 by crowdfunding and wanted to really kickstart the project.
'We're going to have bird boxes all over this area - we're trying to create a wildlife haven throughout the school. It gets children thinking about how we care for our environment and how to make the most of a garden space.
'The pupils are all really enthusiastic about the project and they can't wait to get stuck in with their new garden.
'Everyone has been working together and it's wonderful to see. We certainly wouldn't have got this done without the help of Forgotten Veterans UK.'
The charity offers support to all veterans and their families, either helping them directly or signposting them to the services they need.
The team is based out of Fort Cumberland in Eastney, helping people through financial hardship, health and housing issues and advise on benefits and employment issues.
Gary Weaving, CEO and founder of the Forgotten Veterans UK, enlisted the help of Royal Navy staff with the blessing of Commander Bailey.
He said: 'This has been a very theraputic experience for all of us.
'Many of our guys have lost an awful lot, so it's been great for them to get out and for the navy to get to know them.
'Working with the children has been an absolute pleasure for all of us - to show them what we're doing and how to do it but also educating them on the veteran community.'
As a thank you to the veterans, the school is planning to hold a fundraising non-school uniform day in the near future.