Almost half of the "bayonet strength" of the Royal Regiment of Scotland is being sent to Afghanistan to take part in a pivotal spring campaign which could make or break Nato's strategy for driving the Taliban from their southern heartland.

As revealed exclusively by The Herald last week and confirmed yesterday by the Ministry of Defence, the Argylls and the Royal Highland Fusiliers have each been committed in battalion-strength, while the Highlanders are to supply a reinforced Warrior company group.

The Scots Dragoon Guards are also sending an armoured squadron to provide firepower and protection for the ground force. It means that between 1200 and 1300 Scottish infantry and 120 cavalrymen will be in the forefront of fighting the Taliban. There are currently 2942 soldiers in the RRS's five battalions.

The Scots will come under the command of 16 Air Assault Brigade and will represent 40% of its offensive power.

The 2nd and 3rd battalions of the Parachute Regiment and 1st battalion, the Royal Irish Regiment, are the other main ground units.

In addition, the airborne gunners of the Royal Horse Artillery and "elements" of four other artillery regiments, plus the Paras' specialist Pathfinder Platoon, will provide fire support, target identification and reconnaissance capabilities.

What the MoD did not announce is that the bulk of the SAS and its 600-strong Special Forces Support Group - in effect, the Paras 1st battalion - will also be in action.

Part of their mission is believed to involve targeting the mid-level drug traffickers using opium production to help bankroll the insurgents.

It will be the first time since the end of the Second World War that all three Para battalions have operated in the same war zone.

Since all three of the Scottish battalions involved are currently the worst-manned in the RRS, with a collective shortfall of 277 trained men, volunteers from other battalions and Territorials are being drafted in to make up the numbers for front-line duty.