Hundreds of men from Taunton-based 40 Commando are training in the deserts of California. Next May they become Britain's high readiness unit which can be deployed anywhere in the world at a moment's notice.
They'll also be doing jungle and cold weather training in Gabon and Norway in the months ahead.
Thousands of people lined the streets of Taunton today, as 700 Royal Marines marched through the town to officially mark the end of their time in Afghanistan.
The Marines from 40 Commando were the very first to be deployed to the country twelve years ago.
This year, after four tours of duty, they're among the last to return.
Bob Cruwys reports:
Sixteen families lost loved ones serving with 40 Commando in Afghanistan. But the unit was by no means the only one to be affected by the conflict.
Families from across our region lost sons, brothers and fathers, who were serving in military units based across the South West.
Ahead of today's parade our Somerset Correspondent David Woodland spoke to Judy Gaden, the mother of Corporal Tom Gaden, who was killed in Afghanistan four years ago:
The Duke of Edinburgh will be presenting medals to the Royal Marines at a private ceremony at Norton Manor Camp.
Our Somerset correspondent David Woodland is there:
Thousands of people have turned out in Taunton to welcome home the Royal Marines of 40 Commando from Afghanistan.
700 Marines paraded through the town's streets which were lined with huge crowds.
The troops were among the very first deployed to the country nearly 12 years ago. Now, after four tours they are among the last to return.
Bob Cruwys reports:
The Duke of Edinburgh will present medals to Royal Marines from 40 Commando in Taunton later. A homecoming parade will also take place on the High Street to mark their return from Afghanistan.
It will be a chance to remember the 18 Royal Marines who lost their lives during the decade-long conflict.
A parade to welcome home 40 Commando Royal Marines will take place in Taunton tomorrow and will be attended by thousands of people.
Road closures and diversions will be in place from 7.30 am so do leave time for your journey.
Buses and taxis will be using temporary stops while cyclists should find alternative places to lock their bikes. There's more information here.
700 Royal Marines just back from Afghanistan have been rehearsing for their parade through the streets of Taunton tomorrow.
40 Commando were the very first troops into Afghanistan, and are among the last out after completing four tours of duty over the past twelve years.