He was an irreverent teenager with a pregnant girlfriend when the idea first crossed his mind: Join the Army, raise a family. She had an abortion, but the idea remained. Patrick S. Fitzgibbon, Saint Paddy to his friends, became Private Fitzgibbon. Three months out of basic training, he went to war.

From his outpost in the Kandahar Province of Afghanistan, he complained to his father about shortages of cigarettes, Skittles and Mountain Dew. But he took pride in his work and volunteered for patrols. On Aug. 1, 2009, while on one of those missions, Private Fitzgibbon stepped on a metal plate wired to a bomb buried in the sunbaked earth. The blue sky turned brown with dust.

The explosion instantly killed Private Fitzgibbon, 19, of Knoxville, Tenn., and Cpl. Jonathan M. Walls, a 27-year-old father from Colorado Springs. An hour later, a third soldier who was helping secure the area, Pfc. Richard K. Jones, 21, of Roxboro, N.C., died from another hidden bomb. The two blasts wounded at least 10 other soldiers.

On Tuesday, the toll of American dead in Afghanistan passed 1,000, after a suicide bomb in Kabul killed at least five United States service members. Having taken nearly seven years to reach the first 500 dead, the war killed the second 500 in fewer than two. A resurgent Taliban active in almost every province, a weak central government incapable of protecting its people and a larger number of American troops in harm’s way all contributed to the accelerating pace of death.