NEW YORK (CNN) -- Thousands of photographic negatives documenting the Spanish Civil War by famed photographer Robert Capa, presumed lost for decades, have found a permanent home at a photography center founded by Capa's brother.
The 4,000 nitrate negatives in Capa's "Mexican suitcase" -- actually three cardboard boxes, hand-fitted for film and meticulously labeled by hand -- began their long journey in Paris in 1939, eventually ending up in Mexico City, where they resurfaced in the late 1990s.
After years of negotiations, the priceless negatives came to the International Center of Photography, founded in 1974 by Capa's brother, Cornell Capa, also a photographer. Take a look at some of the negatives »
"To rediscover these after they were presumed lost for so many years is an extraordinary thing," said Brian Wallis, chief curator of the center.
The "Mexican suitcase" contains negatives of two pre-eminent wartime photographers besides Robert Capa, Gerda Taro and David Seymour.
Taro, one of the first female war photojournalists, "was an extremely accomplished photojournalist in her own right and very successful in her own time" Wallis said. Taro was killed in the battle in the summer of 1937, "and it is a tragedy that she died so young. She was only 26 years old."
The Spanish Civil War was the first conflict for photojournalist Capa -- born Endre Friedmann in Hungary in 1913 -- but he also covered the second Sino-Japanese War, World War II across Europe, the 1948 Arab-Israeli War and the first Indochina War.
Carrying with him the mantra "if your pictures aren't good enough, you're not close enough," Capa embedded himself in the trenches of war, capturing the struggle and tragedy of the everyday soldier. In the process, he redefined the standard for war pictures.
Capa's images were printed in magazines and newspapers from London to New York.
"He sort of set the style and the model for the heroic photojournalist," Wallis said. Watch Wallis display the "Mexican suitcase," describe the images' significance »
One of Capa's most popular images, "The Fallen Soldier," has been contested since its publication in 1936. The image of a soldier the moment he is shot in the chest was suspected of being staged. If the negative of this famous image can be located in sequence with other negatives, any such questions could be answered.
Capa was a methodical and devoted war photojournalist, but he was also "a real man about town, a bon vivant, the guy everyone wanted to know and hang out with," according to Wallis, who said Capa was known to socialize with the likes of authors Ernest Hemingway and John Steinbeck.
Capa originally wanted to be a writer, but he grew to love photography after finding work as a photographer in Berlin, where he settled after being arrested for his political activities in Hungary.
Capa, who was Jewish, left Berlin for Paris because of the rise of the Nazis, but fled the City of Lights for the United States in 1939 as the Nazi threat loomed.
When he left, he entrusted his negatives to his darkroom manager, who is believed to have fled south to Marseilles, where he was captured as a prisoner of war. He left the negatives with a Mexican diplomat in the French city, and that diplomat eventually brought them to Mexico City, where they surfaced in the possession of a filmmaker in 1995.
Capa died in 1954, believing the images had been lost in the Nazi invasion of France in 1940.
Finding this legendary "suitcase" was something akin to finding a sketch book from Picasso or a lost musical manuscript by Beethoven, Wallis said. The negatives allow historians, archivists and photographers to gain a deeper understanding of Capa's work.
The negatives are remarkably well preserved, Wallis said, crediting the dry air in Mexico City as the likely agent that left the them "pliable and fresh." For their continued preservation, the center consulted conservation experts from the George Eastman House in Rochester, New York, Wallis said. E-mail to a friend