December 29, 2014 4:09 PM EST

The United States-led coalition in Afghanistan ended its combat mission on Sunday, 13 years after it began in the wake of the Sept. 11 attacks. More than 10,000 troops will remain on the ground to aid Afghan forces in a new U.S. role that called Operation Freedom’s Sentinel.

“For more than 13 years, ever since nearly 3,000 innocent lives were taken from us on 9/11, our nation has been at war in Afghanistan,” President Barack Obama said in a statement. “Now, thanks to the extraordinary sacrifices of our men and women in uniform, our combat mission in Afghanistan is ending, and the longest war in American history is coming to a responsible conclusion.”

Almost 1 million U.S. troops served at least one tour in Afghanistan; a total 3,485 allied troops were killed, including 2,356 Americans.

Reuters photographer Lucas Jackson documented the final days of the U.S.’s official combat campaign with the men and women of Forward Operating Bases Gamberi and Fenty in Laghman and Nangarhar provinces, respectively.

Read next: U.S. Ends Its War in Afghanistan

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