On April 18, 2002, "friendly fire" killed four Canadian soldiers in Afghanistan, Canada's first combat deaths since the Korean War.

On April 18, 2002, Alpha Company, Third Battalion of the Princess Patricia's Canadian Light Infantry, was on a training exercise at Tarnak Farms, a former Taliban artillery range in southern Afghanistan. The exercise had been underway for nearly seven hours when two American fighter pilots flew overhead. One, Major Harry Schmidt, saw the artillery fire below, and thinking he was under attack, dropped a laser-guided bomb.

Four Canadian soldiers died that night, the first Canadian combat fatalities since the Korean War. For many in Canada the tragedy signalled the true beginning of Canada's lengthy combat mission in Afghanistan.

First Soldiers Down recounts what happened that evening through archival material and the recollections of troops. It also tells the personal stories of the fallen Sergeant Marc Lger, Corporal Ainsworth Dyer, Private Richard Green, and Private Nathan Smith as well as what happened to the loved ones of each of the four in the decade since the incident.