UK troops working as part of the International Security Assistance Force (ISAF) in southern Afghanistan have been taking part in a joint operation with US Marines aimed at disrupting Taliban activity in the volatile Garmsir area of Helmand province.

Troops from 16 Air Assault Brigade joined the Marines, from the US 24th Marine Expeditionary Unit (MEU), as they pushed south of Garmsir where currently, but for a few border security police, neither ISAF nor the Afghan Security Forces have a presence. The purpose of the operation was to extend security authority further south towards the Pakistan border.

Although British framework operations are currently focused further north, in the areas of Lashkar Gar, Sangin, Gereshk and Musa Qaleh, the British Task Force has had an important role to play facilitating the move of the MEU down through the province.

This type of operation, known as a Forward Passage of Lines, is generally believed to be one of the most complex, involving as it does the initial movement of large amounts of men and equipment long distances across potentially hostile ground and then passage through the positions of the force already deployed on the ground, in this case C Company.

Large convoys are extremely vulnerable and the slightest delay or mishap can have serious repercussions. Thorough planning is essential, particularly in a multi-national context. The Royal Regiment of Scotland, largely responsible for executing the passage on the ground, had neither trained nor operated with the Marines before.

Led by the Task Force Headquarters under 16 Air Assault Brigade, every piece of detail was picked over by British and American commanders and staff officers, shuttling between Helmand and Kandahar to ensure the operation went smoothly. When the time came the Marines, in an initial move, drove south and assembled at Forward Operating Base (FOB) Dwyer, ready to conduct their passage through British lines and across the Helmand River.

So, in the early hours of Wednesday morning, 30 April 2008, the operation began, with a narrow and precarious bridge crossing over the Helmand River, the first obstacle. With their knowledge of the ground and expertise in marking a safe route, the UK troops played a vital part in proceedings.

Other elements of the Task Force also played a significant part: soldiers of 7 Royal Horse Artillery, as well as being prepared to provide artillery support, have taken the lead de-conflicting different parts of the battle space to avoid any possibility of friendly fire; and British engineers from 23 Regiment also stood by to assist with clearing the route of roadside bombs or to lay bridges over the Helmand River if required. Back at Camp Bastion, the British Field Hospital and, in particular the Medical Emergency Response Team (MERT), supporting the Marines' own medical capability, stood by to evacuate any casualties.

UK military spokesman, Lieutenant Colonel Robin Matthews, explained the UK involvement in this latest operation:

"We had people up at Kandahar air base integrated into their (24 MEU) planning, helping to shape the operation. We've got two years of experience of Helmand, knowledge of the people and the terrain, which was a vital part of the planning process. All of this was fed into the planning to help them identify how to conduct the operation to best effect.

"The Brigade also contributed a lot in terms of intelligence and knowledge in advance. We were using our Unmanned Aerial Vehicles (UAVs) to give surveillance intelligence, and then cover for the route. We also used the intelligence we gathered from patrols around FOB Dwyer near Garmsir to get an understanding of the local atmosphere.

"For the actual operation, the US Marines travelled from Bastion down to FOB Dwyer and then to FOB Delhi under their own steam. From there 5 Scots under the Command of 2 Scots Commanding Officer Lieutenant Colonel Nick Borton provided route planning and marking.

"23 Regiment Royal Engineers provided Explosive Ordnance Disposal teams. They were also on standby for engineering support where needed, including being ready to put in a new bridge if required. We also provided vehicle recovery teams and a medical team in case things got difficult.

"The convoy travelled from Bastion to Dwyer to Delhi, and a great deal of planning went into sorting out how to accommodate and support them as they went. Convoy logistics patrols went ahead to Delhi to make sure there were supplies in place, although mostly the Marines had to be reasonably self-sufficient.

"The Marines left FOB Delhi under darkness to traverse the last part of the route where the UK gave support, down into Garmsir. They had to traverse a narrow and vulnerable bridge, and the fact that they got all their vehicles across without mishap is a testament to the good planning of Task Force Helmand and the MEU."

Colonel Pete Petrozio, Commanding Officer of 24 MEU, added:

"This is what alliances are all about, professionals coming together to achieve the right effect.