It was a sneak attack, but not by the enemy they feared.
Army Capts. Joshua Lawrence and Drew Russell were inside a small command post on an Afghan army base, wrapping up a long day of coordinating the safe arrival of nearly 100 Afghan religious and tribal leaders for a peace conference at a nearby palace.
Darkness had fallen. Some of their fellow soldiers had retired for the evening. Two stood guard.
All seemed well.
But as several soldiers sprawling on nearby cots played cards, the calm collapsed catastrophically at 9:27 p.m.
An exploding grenade shattered the stillness, followed in seconds by bursts of gunfire. Before any of the Americans could raise a hand in self-defense, Capt. Lawrence was dead from a bullet to the head, and Capt. Russell was dying, shot three times in the back.
They were not killed by the Taliban, as the U.S.-led military coalition indicated the day after the Oct. 8, 2011, assault.
Capt. Lawrence, 29, of Nashville, Tenn., and Capt. Russell, 25, of Scotts, Mich., were killed in what U.S. investigators later called a "calculated and coordinated" attack by Afghan soldiers entrusted to work alongside their U.S. partners.
This is the first published account of the attack and is based on internal Army records and interviews in the U.S. and Afghanistan.
For Capt. Russell's family, the anguish is still fresh. His father, Jim, said the loss was even harder to accept after learning from the Army's investigation report early this year that it was a supposed ally, not the Taliban, who killed his son.
"It wasn't like a battle, you know. He pretty much got ambushed," he said, pausing at length to settle his emotions. "That makes it difficult."
On that moonlit Saturday evening, Capt. Russell was the designated "battle captain," or duty officer, in the command center. Capt. Lawrence worked beside him as a plans officer.
Both were members of the 4th Infantry Division's 2nd "Warhorse" Brigade. They deployed to Afghanistan in June 2011. Capt. Lawrence had married just one week before leaving; the honeymoon was to wait until he returned home.
The Associated Press learned details of the attack from formerly secret Army investigation records obtained through the Freedom of Information Act. The Army removed substantial portions of the documents to protect what it called properly classified information as well as the identities of most people involved. The AP established some identities on its own.
The investigation – a standard process in a war zone – found that security at the U.S.-Afghan command post was so relaxed that guards were not told to check anyone entering.
Afghan thievery, not treachery, was judged the chief threat. Thus the killers had unfettered access and moved about without arousing suspicion.
Only 10 designated Afghan security personnel were supposed to be in the compound, but U.S. guards were given no access roster. Unknown numbers "freely entered and exited the compound unchecked," an Army investigator found.
The Americans had been told to treat the Afghans as if they were mingling in Iron Horse Park, a recreation area on their home base, Fort Carson, Colo., according to a staff sergeant who was present but whose name is blacked out on his sworn statement to investigators.
The Americans had convinced themselves, 10 years into a war in which the successful outcome depended on empowering local security forces, that they could trust their Afghan colleagues.
That was a deadly miscalculation in this instance and dozens more in the months that followed as growing numbers of Afghan troops turned their guns on their coalition partners.
As the attacks mounted this year, U.S. officials in Kabul and Washington insisted that these were "isolated incidents." They routinely withheld details and, until pressed by the AP, did not publicly disclose attacks in which coalition troops were wounded but not killed.
At least 63 coalition troops – mostly Americans – have been killed, by the AP's count, and more than 85 wounded in at least 46 insider attacks so far this year. That is an average of nearly one attack a week.
In 2011, 21 insider attacks killed 35.
The attack that killed Capts. Lawrence and Russell in the southern city of Kandahar was the 17th of 2011.