Cosplayers dressed as characters from the Star Wars movie series visit patients during a charity event organised by non-profit group 501st Legion, at East Avenue Medical Center in Quezon city, metro Manila December 6, 2015. (Photo by Romeo Ranoco/Reuters)

Medic James E. Callahan of Pittsfield, Mass., gives mouth-to-mouth resuscitation to a dying soldier in war zone D, about 50 miles northeast of Saigon, June 17, 1967. Thirty-one men of the 1st Infantry Division were reported killed in the guerrilla ambush, with more than 100 wounded. (Photo by Henri Huet/AP Photo)

Revellers dressed in mock military garb take part in the “Els Enfarinats” battle in the southeastern Spanish town of Ibi on December 28, 2017. During this 200-year-old traditional festival participants known as Els Enfarinats (those covered in flour) dress in military clothes and stage a mock coup d'etat as they battle using flour, eggs and firecrackers outside the town hall as part of the celebrations of the Day of the Innocents. (Photo by Jaime Reina/AFP Photo)

A US Marine leads two Viet Cong suspects in restraints during the Tet Offensive on February 20, 1967. (Photo by Bettmann Archive/Getty Images)

A reveller takes part in the battle of “Enfarinats”, a flour fight in celebration of the Els Enfarinats festival on December 28, 2015 in Ibi, Spain. Citizens of Ibi annually celebrate the festival with a battle using flour, eggs and firecrackers. (Photo by Pablo Blazquez Dominguez/Getty Images)

Lava erupts from the Piton de la Fournaise “Peak of the Furnace” volcano, on the southeastern corner of the Indian Ocean island of Reunion Saturday, August 1, 2015. Spewing red-hot lava, one of the most active volcanoes in the world is currently erupting on this Indian Ocean island, where the world's attention has been focused since a wing fragment believed to be from the missing Malaysian jet was discovered washed up on a beach. The lava fountains are shooting as high as 40 meters (44 yards) and are creating cones that are about 20 meters high after only one day of eruption, said Peltier. The volcano is in the Reunion National Park – a world heritage site. The volcano is not seen as dangerous because the lava flows down the east side of the mountain through an uninhabited area called the Grand Brule, or the Big Burned, toward the sea. The last times the volcano threatened the population was in 1977 and 1986. (Photo by Ben Curtis/AP Photo)

Shephen Shine, 27, who lost a leg when serving in Iraq in 2007, is tattood with a regimental tattoo reading “Their Sacrifice – Our Freedom” during the Ink For Heroes event on June 18, 2011 in Catterick, England. Ink For Heroes is a charity event to raise money and awareness of the soldiers that get injured during service, with all proceeds going to both “Help The Heroes” and “The British Legion”. Injured soldiers can also get tattooed for free during the event. (Photo by Bethany Clarke/Getty Images)

Construction continues on One World Trade Center (TALLEST BUILDING AT LOWER LEFT) as the memorial footprints of the twin towers are seen (BOTTOM C) on August 12, 2011 in New York City. Upon completion, One World Trade Center will be New York's tallest skyscraper, topping out at a symbolic 1,776 feet, with 3 million square feet of office space. More than 2,700 people were killed when al-Qaeda terrorists hijacked U.S. passenger jets and flew them into the twin towers of the World Trade Center on September 11, 2001. Nearly ten years after the crippling attacks on Lower Manhattan, business, tourism and new construction like One World Trade Center have rejuvenated the formerly devastated cityscape.(Photo by Mario Tama/Getty Images)