Operation Herrick

Operation Herrick was the operational name for the British Armed Forces' operations during the War in Afghanistan, from 2002 to the end of combat operations in 2014. It consisted of the British contribution to the multinational NATO-led International Security Assistance Force (ISAF) mission for the purposes of local security, training and development, and support to the American-led Operation Enduring Freedom (OEF) counterterrorism mission. After years in the field, Operation Herrick increased in size and breadth to match ISAF's growing geographical intervention in Afghanistan: British troops numbered 9,500 at its peak in 2010–2012. The operation has also been referred to as the Fourth Anglo-Afghan War.

Initially, the operation consisted mainly of security in Kabul and training of the Afghan National Army until it grew into a battalion when British troops took over the PRT for northern Afghanistan. As of 2004, there were some 400 British personnel in Afghanistan, rising to 900 in 2005. With the expansion of ISAF operations, over 3,000 British troops were deployed to the volatile, heroin-rich province of Helmand in southern Afghanistan from April 2006 to lead the local PRT, with Britain also on a leading role in counternarcotics. Intended to be a civilian reconstruction mission, British troops were unexpectedly forced to engage in heavy combat with Taliban militants who fiercely resisted their presence, fueled in part by local resentment from colonial-era conflict. Heavy fighting in the summer of 2006 during the Siege of Sangin was described as the fiercest the British army had faced since the Korean War. While there had only been five British fatalities in Afghanistan up until that point, in 2006 alone this number escalated to 39 deaths and kept increasing annually, peaking at over one hundred each in 2009 and 2010. Troop numbers during Operation Herrick rose to 8,000 in 2008 and later at over 9,000.

The UK began withdrawing throughout 2013, continuing until the last of its combat troops left Afghanistan on 27 October 2014. Following this, British military operations in Afghanistan focused on training as part of Operation Toral, the UK's contribution to the NATO Resolute Support Mission, which continued until the ultimate countrywide 2021 Taliban victory after the defeat of the Islamic Republic of Afghanistan. A total of 454 British personnel had died on operations in Afghanistan from 2002 to 2014, outnumbering the amount killed during the Iraq and Falklands wars. While British involvement in Afghanistan had solid support politically and from the public, there was criticism for strategic military failures of the Helmand campaign, its resulting death toll, and the lacklustre "war on opium".