Wolves were reintroduced into Yellowstone National Park in 1995. It was the start of one of the most famous and controversial wildlife restoration projects in the United States. Beginning in the late 19th century wolves had been subjected to a mass extermination programme as ranchers feared the wolf was a threat to their livestock. By the mid 20th century, wolves had effectively been wiped out across the country except for a few isolated pockets in the far north. But the loss of this key predator had a profound impact on the ecosystem. Alex Last has been speaking to Doug Smith, Senior Biologist at Yellowstone National Park, and Wolf Project Leader about the return of the wolf.

Photo:.A Yellowstone wolf watches biologists after being tranquilized and fitted with a radio collar during wolf collaring operations in Yellowstone National Park (William Campbell/Sygma via Getty Images)

On August 25 1944 General Charles De Gaulle, who had been in exile in London for the majority of World War 2, finally entered Paris at the head of the Free French forces. But the French capital was far from secure. Ashley Byrne hears from Charles Pegulu de Rovin, who as an 18-year-old student fought with other resistance fighters against the Nazis in the final battle for Paris.

(Photo by Pierre Jahan/Roger Viollet via Getty Images)

At the end of El Salvador's civil war human rights investigators began the search for hundreds of children reportedly kidnapped by the army during anti-guerrilla operations. In early 1994, two years after the end of the conflict, the first six children were located in an orphanage in the capital San Salvador. Among them was Maria Elsy Dubon, who had been seized by soldiers who killed her father in May 1982. Mike Lanchin has been hearing about Maria Elsy's distressing ordeal and about the difficult reunion she later had with her biological family, who believed that she was dead.

(Photo: Peasants who lost their children during military operations in the civil war at a rally in March 2006 (YURI CORTEZ/AFP/Getty Images)

In 1998, a transponder or silicon chip was surgically implanted into the forearm of a British scientist. It sent identifying signals to a central computer that tracked his movements and allowed him access to his workplace, by opening doors and switching on lights. Professor Kevin Warwick has been speaking to Farhana Haider about becoming a more enhanced version of himself and as a result the world's first Cyborg: a man-machine hybrid.

Photo: Professor Kevin Warwick with chip transponder Credit: Science Photo Library

The Dr Seuss books revolutionised the way American children learnt to read in the 1950s. Books like 'The Cat in the Hat' were designed to help young children enjoy reading simple words and sentences using rhymes, anarchic characters and lively illustrations. Claire Bowes spoke to Christopher Cerf who knew Theodor Geisel, the author of the books.

Photo: Author and illustrator Ted Geisel sits at his drafting table with a copy of his book, 'The Cat in the Hat' in 1957. (Gene Lester/Getty Images)

In the 1980s Ilich Ramírez Sánchez known as 'Carlos the Jackal' was seen as the world's most-wanted terrorist. He had carried out bombings, killings and kidnappings and had been on the run for decades. He was finally arrested in Khartoum in August 1994. Alex Last spoke to former CIA operative, Billy Waugh, who tracked him down.

Photograph: Rare photo of Carlos the Jackal, taken in the 1970s (AFP/Getty Images)

Throughout 2001 the US authorities were being given warnings that a terror attack was imminent. A Congressional Commission, FBI officers and the CIA were all worried. There were even specific warnings about planes being flown into buildings. Louise Hidalgo has been speaking to former Senator Gary Hart who co-chaired the Congressional Commission that tried to convince the government to take action.

Photo: Smoke pours from the World Trade Centre after it was hit by two passenger planes on September 11, 2001 in New York City. (Credit: Robert Giroux/Getty Images)

The contact lens was once a precious and expensive piece of eyewear which had to be looked after and carefully cleaned every night. But that all changed in the 1990s. Ron Hamilton was involved in developing lenses and packaging which could be made so cheaply they could be worn just once and then thrown away. He has been speaking to Ashley Byrne.

Photo: Ron Hamilton (l) with his business partner Bill Seden (r) and their wives with their original contact lens machine. Courtesy of Ron Hamilton.

In October 1947, an invasion of Kashmir by tribal fighters led to the division of the state between India and Pakistan. Andrew Whitehead speaks to victims of the invasion and political leaders in Kashmir to find out more about the roots of a crisis that endures to this day.

PHOTO: Indian troops arriving in Kashmir in October 1947 (Getty Images)

In 1949 a British warship, HMS Amethyst, launched a daring escape after it was held captive for months by Chinese Communists on the Yangtze river. The ship had been badly damaged when it was fired on by Communist forces as it sailed up the river to help evacuate British citizens from Nanking during the final months of China's civil war. Using eyewitness accounts in the BBC Archive, we tell the story of HMS Amethyst.

Photo: The HMS Amethyst (F116) arrives in Hong Kong after it's epic escape down the Yangtse. (Photo Hulton-Deutsch Collection/CORBIS/Corbis via Getty Images)