The Race2Recovery team is trying to complete the Dakar Rally to raise funds for Help for Heros.
The charity is raising funds for the Tedworth House recovery and rehabilitation centre in Wiltshire.
The two US Marines involved with the race are also raising funds for the Heros Project which supports injured service men and women in America.
More top news
The dangerous Khumbu icefall has been rendered impassable after an avalanche, trapping climbers on Mt Everest. Here's what you need to know.
A company included in a letter supporting the Tory Party said one of its staff members had been wrongly listed as a signatory.
Customs officials in Thailand seize 3 tons of ivory hidden in tea leaf sacks from Kenya in the second-biggest bust in the country's history.