Royal Marines from 40 Commando have returned home after six months in Afghanistan.
During the operation, 14 marines from the base at Norton Fitzwarren in Somerset were killed and 11 were seriously injured.
About 600 marines had been serving since April in the Sangin area of Helmand Province before it was taken over by US forces in September.
The first set of marines arrived in Taunton at about 1400 BST.
The rest of the marines will return over the next week.
Major Duncan Forbes said: "It's a bittersweet day being back here; 21 people from the battle group were killed and 14 of them were Royal Marines.
"Their sacrifice was not made in vain; they did an amazing job every day showing bravery and leadership, which is humbling for us as their leaders to look to.
"It's a sad day for those families who have not got their husbands coming back."
The Marines, part of 3 Brigade, were deployed to Sangin in April under the command of 4 Mechanised Brigade on Operation Herrick 12.
Sangin, a key economic and transport hub in southern Afghanistan, has been the scene of the bloodiest fighting by British troops, accounting for almost a third of the 339 deaths since 2001.
Sgt Andy Hughes from Cotford St Luke, near Taunton, returned earlier after completing his fourth tour in Afghanistan.
He said: "My eyes are still adjusting to the contrast and the colours instead of the browns and yellows of being out in the the desert in Afghanistan."
Speaking of their losses, one marine said: "There have been some really bad days, especially when one of our lads got killed.
"It's hard not to give up. I kind of block it out until we're home safe and then I'll start mourning."
Emma Forbes, who gave birth during her husband's deployment, has been keeping a blog detailing her experience.
In her latest entry, Mrs Forbes said: "This has been a gruelling six months and my prayers are with the families whose loved ones are not coming home.
"I expected to feel simple, childish joy and anticipation as I count down the days and hours (and I do). However, going through a deployment with small children has made me acutely aware of the sacrifice all of the guys make."
After their return home, the marines will have three weeks off before returning to march through Taunton town centre on 17 November.