Definition: In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
Input: KORENGAL VALLEY, AFGHANISTAN -- It was as if the five years of almost ceaseless firefights and ambushes had been a misunderstanding -- a tragic, bloody misunderstanding. 
  
 More than 40 U.S. troops have been killed, and scores more wounded, in helicopter crashes, machine-gun attacks and grenade blasts in the Korengal Valley, a jagged sliver just six miles long and a half-mile wide. The Afghan death toll has been far higher, making the Korengal some of the bloodiest ground in all of Afghanistan, according to American and Afghan officials. 
  
 In the pre-dawn hours of Wednesday, the U.S. presence here came to an abrupt end. 
  
 A day earlier, Capt. Mark Moretti, the 28-year-old commander of American forces in the valley, walked two dozen Korengali elders around his base and told them that the United States was withdrawing. He showed the elders the battle-scarred barracks, a bullet-ridden crane, wheezing generators and a rubber bladder brimming with 6,000 gallons of fuel. 
  
 Moretti, the son of a West Point physics professor, and Shamshir Khan, a valley elder whose son had been jailed for killing two U.S. troops, sat together on a small wall near the base's helicopter pad. In keeping with local custom among friends, they held hands. 
  
 Moretti gently reminded Khan of the deal they had reached a few days earlier: If U.S. troops were allowed to leave peacefully, the Americans wouldn't destroy the base, the crane and the fuel. Khan assured him that the valley's fighters would honor the deal. 
  
 "I hope that when I am gone, you will do what is best for your valley and the villagers," an almost wistful Moretti said. 
  
 "I want you to travel safely to your home, to your family," the 86-year-old elder replied. He gazed at the officer through thick glasses that magnified rheumy brown eyes and beamed. 
  
 Over the previous week, hundreds of U.S. Army Rangers and Afghan commandos had pushed into the valley to control the high ground the enemy would need for a big attack on departing troops. Dozens of cargo helicopters hauled off equipment. By Wednesday morning, the last Americans were gone. 
  
 For U.S. commanders, the Korengal Valley offers a hard lesson in the limits of American power and goodwill in Afghanistan. The valley's extreme isolation, its axle-breaking terrain and its inhabitants' suspicion of outsiders made it a perfect spot to wage an insurgency against a Western army. 
  
 U.S. troops arrived here in 2005 to flush out al-Qaeda and Taliban fighters. They stayed on the theory that their presence drew insurgents away from areas where the U.S. role is more tolerated and there is a greater desire for development. The troops were, in essence, bullet magnets. 
  
 In 2010, a new set of commanders concluded that the United States had blundered into a blood feud with fierce and clannish villagers who wanted, above all, to be left alone. By this logic, subduing the Korengal wasn't worth the cost in American blood. ||||| KORENGAL OUTPOST, Afghanistan—For five years, U.S. troops fought their way up and down the cedar-studded slopes of the Korengal Valley. The ferocity of the fighting inspired a video-game scenario, thrust the remote valley into the media glare, and famously forced a U.S. soldier to fight in his underwear. In all, 42 U.S. troops have been killed here. 
  
 On Wednesday, the fight for Korengal officially ended when the final U.S. soldiers were airlifted from a ridge above this collection of stone buildings, sandbagged bunkers and jury-rigged plumbing built on the grounds of a former lumber mill. The Americans pulled out because ... |||||
Output:
The last US troops left Korengal Valley this morning, ending five years of seemingly pointless combat. Before dawn an American captain showed local village elders around what used to be the US base, the Washington Post reports, showing them the bullet-ridden crane and full fuel bladder they’d traded for an unmolested passage out of the valley. Since 2005, 42 Americans have died in the valley—and many more Afghans. US troops originally came here to drive out al-Qaeda, but they stayed on the theory that they could draw enemy fighters away from areas that were more important. But now Stanley McChrystal says he believes they were just an “irritant to the people,” instigating combat by their mere presence. “I care deeply about everyone who’s been hurt here,” he tells the Wall Street Journal. “But I can’t do anything about that. I can do something about people hurt in the future.”