A Green Crowned Brilliant is pictured at a Hummingbird feeding station on January 15, 2016 in Alajuela Costa Rica. Of the 338 known species of Hummingbird worldwide there are around 50 in Costa Rica. Hummingbirds are named for the distinctive sound made by their tiny beating wings, and are admired for their vibrantly coloured iridescent plumage. Their ability to hover, with wings beating between 12 and 90 times a second, and to fly backwards makes them different from all other birds. (Photo by Dan Kitwood/Getty Images)

This adorable gallery reveals the astonished expressions of dozens of puppies as they try to gobble up treats flying through the air toward them. Photographer Christian Vieler, 48, has been documenting pooches, with their eyes bulging, mouths wide open and looks of love on their faces, in his studio as part of the project “Dogs Catching Treats” since 2013. (Photo by Christian Vieler/Caters News Agency)

“G.I. Joe is a line of action figures produced by the toy company Hasbro. The term G.I. stands, in popular usage, for Government Issued and after the First World War became a generic term for U.S. soldiers. The origin of the term dates to World War I, when much of the equipment issued to U.S. soldiers was stamped “G.I.”, meaning that it was made from galvanized iron. The development of G.I. Joe led to the coining of the term “action figure”. G.I. Joe's appeal to children has made it an American icon among toys”. – Wikipedia. Photo: Vintage G.I. Joe figurers are on display at the 2003 Hasbro International G.I. Joe Collectors' Convention June 27, 2003 in Burlingame, California. (Photo by Justin Sullivan/Getty Images)

General view of the monument to memory of soldiers who liberated the city of Knin – in Knin, Croatia on November 10, 2014. Across the former Yugoslavia stand giant monuments to a state that no longer exists, once visited and celebrated during public holidays such as Republic Day on November 29, marking the creation of socialist Yugoslavia. Many are now neglected or ignored, aging symbols of a joint state forged during World War Two but torn apart by nationalism half a century later. Republic Day is no longer marked in any of the seven independent states that emerged from its ashes. (Photo by Antonio Bronic/Reuters)

Performers wearing 19th century French military uniforms fire their weapons as they attack Allied forces during a reenactment of the Battle of the Nations, in a field in the village of Markkleeberg near Leipzig October 20, 2013. The east German city of Leipzig commemorated the 200th anniversary of the largest battle of the Napoleonic Wars on Sunday by reenacting the Battle of the Nations, with 6,000 military-historic association enthusiasts from all over Europe. The decisive encounter in which tens of thousands of soldiers were killed, took place from October 17-19, 1813, just outside of Leipzig. At the height of the hostilities Napoleon fielded more than 200,000 men against an Allied force of some 360,000 soldiers which included troops from Russia, Austria, Prussia and Sweden. (Photo by Fabrizio Bensch/Reuters)

Students carry a female trainee who has fallen into a stupor during high intensity training at Tianjiao Special Guard/Security Consultant camp on the outskirts of Beijing December 1, 2013. Former Chinese soldier Chen Yongqing has big ambitions for his bodyguard training school Tianjiao, which he says is China's first professional academy to train former soldiers and others as personal security guards. Chen charges 500,000 yuan ($82,400) a year for each protector as China's rich and famous look to bolster their safety and sense of importance. (Photo by Jason Lee/Reuters)

“Eyes Wide Open is an exhibit created by the American Friends Service Committee observing the American soldiers and marines that have died in the Iraq War. It contains a pair of combat boots to represent every American soldier and marine that has died in the war, as well as shoes representing Iraqi civilians who have lost their lives during the invasion and occupation”. – Wikipedia

Photo: A man pauses as he looks at rows of combat boots that are part of the "Eyes Wide Open" exhibit in front of San Francisco City Hall on March 19, 2012 in San Francisco, California. The Eyes Wide Open exhibition includes a pair of boots for every one of the 481 California servicemen and women who died in the Iraq war. (Photo by Justin Sullivan/Getty Images)

“Dover Castle is a medieval castle in the town of the same name in the English county of Kent. It was founded in the 12th century and has been described as the “Key to England” due to its defensive significance throughout history. It is the largest castle in England.

The outbreak of the Second World War in 1939 saw the tunnels converted first into an air-raid shelter and then later into a military command centre and underground hospital. In May 1940, Admiral Sir Bertram Ramsey directed the evacuation of French and British soldiers from Dunkirk, code-named Operation Dynamo, from his headquarters in the cliff tunnels”. – Wikipedia

Photo: The Repeater Station in the subterranean tunnels underneath Dover Castle, which has been restored by English Heritage for a public exhibition on June 3, 2011 in Dover, England. The evacuation of allied soldiers from Dunkirk was masterminded and co-ordinated from the secret command and control centre in the tunnels deep below the castle. (Photo by Matthew Lloyd/Getty Images)