The invasion of Iwo Jima began on February 19, 1945, and continued to March 27, 1945. The battle was a major initiative of the Pacific Campaign of World War II. The Marine invasion, known as "Operation Detachment", was charged with the mission of capturing the airfields on the island, which up until that time had harried U.S. bombing missions to Tokyo. Once the bases were secured, they could then be of use in the impending invasion of the Japanese mainland. The battle was marked by some of the fiercest fighting of the War. The Imperial Japanese Army positions on the island were heavily fortified, with vast bunkers, hidden artillery, and 18 kilometres (11 mi) of tunnels. The battle was the first U.S. attack on the Japanese Home Islands and the Imperial soldiers defended their positions tenaciously. Of the 21,000 Japanese soldiers present at the beginning of the battle, over 19,000 were killed and only 1,083 taken prisoner. One of the first objectives after landing on the beachhead was the taking of Mount Suribachi. At the second raising of a flag on the peak, Joe Rosenthal photographed five Marines: Ira Hayes, Michael Strank, René Gagnon, Harlon Block, Franklin Sousley, and U.S. Navy corpsman John Bradley raising the United States flag on the fourth day of the battle (February 23). The photograph was extremely popular, being reprinted in thousands of publications. It won the Pulitzer Prize for Photography that same year, and ultimately came to be regarded as one of the most significant and recognizable images of the war, and possibly the most reproduced photograph of all time. Within the next month of fighting, three of the Marines raising the flag were killed: Strank, Block and Sousley. Contrary to popular belief, the famous picture of the six men raising the flag was not the first flag raised on the Island. Another, smaller, flag had been raised a few hours earlier by five other Marines who were the first to the top of Suribachi. The second flag was raised by these six after the Secretary of the Navy asked for the original flag to be raised. After the fall of Mount Suribachi in the south, the Japanese still held a strong position throughout the island. General Tadamichi Kuribayashi still had the equivalent of eight infantry battalions, a tank regiment, two artillery, and three heavy mortar battalions, plus the 5,000 gunners and naval infantry. With the landing area secure, more troops and heavy equipment came ashore and the invasion proceeded north to capture the airfields and the remainder of the island. Most Japanese soldiers fought to the death. On the night of March 25, a 300-man Japanese force launched a final counterattack led by Kuribayashi. He was killed in the battle and his body hidden, his ivory handled pistol was captured by one Marine. The Marines suffered heavy casualties; more than 50 were killed and another 119 Americans were wounded. The island was officially declared "secured" the following morning. According to the U.S. Navy, "The 36-day (Iwo Jima) assault resulted in more than 26,000 American casualties, including 6,800 dead." To put that into context, the 82-day Battle of Okinawa lasted from early April until mid-June 1945 and U.S. (five Army, two Marine Corps Divisions and Navy personnel on ships) casualties were over 62,000 of whom over 12,000 were killed or missing, while the Battle of the Bulge lasted 40 days (16 December 1944 – 25 January 1945) with almost 90,000 U.S. casualties consisting of 19,000 killed, 47,500 wounded, and 23,000 captured or missing. After Iwo Jima was declared secured, about three thousand Japanese soldiers were left alive in the island's warren of caves and tunnels. Those who could not bring themselves to commit suicide hid in the caves during the day and came out at night to prowl for provisions. Some did eventually surrender and were surprised that the Americans often received them with compassion — offering them water, cigarettes, or coffee. The last of these stragglers, two of Lieutenant Toshihiko Ohno's men (Ohno's body was never found), Yamakage Kufuku and Matsudo Linsoki, lasted 3-and-one-half years, surrendering on January 6, 1949. The U.S. military occupied Iwo Jima until 1968, when it was returned to Japan. It has been reported that many of the Japanese remains in Iwo Jima are missing their skulls. It is possible that the souvenir collection of body remains continued also in the immediate post-war period. Former and current U.S. Marines gather at the Marine Corps Museum to remember the battle of Iwo Jima in Quantico, Va. Feb. 20, 2015. February 19th marked the 70th anniversary of the start of the battle, which resulted in 27 U.S service members being awarded the Medal of Honor.