WASHINGTON -- By February 1945, U.S. forces had island hopped across the Pacific Ocean and were rapidly closing in on the Japanese mainland.

Before attacking Japan, war planners hoped to capture Iwo Jima, a tiny island in the Western Pacific that would put U.S. bombers within a 750-mile strike range of Japan.

The task for doing this fell to the 3rd, 4th and 5th Marine divisions, the Army's 147th Infantry Regiment and the Navy's 5th Fleet.

Plans to capture Iwo Jima unfolded June 15, 1944, with Army Air Forces and Navy bombardment of the island. This continued until troops landed on the island Feb. 19, 1945, 75 years ago today.

Despite the heavy and sustained bombardment of the island, the Japanese had their own defensive plans, which included about 11 miles of tunnels and underground rooms for command and control and other functions.

So, the bombardment by the Americans of Iwo Jima had relatively little effect on about 21,000 Japanese troops holed up underground.

To make matters worse for the Americans, many of the tunnels were located on the slopes of Mount Suribachi. The Japanese directed artillery, small arms and mortar fire from openings downward on U.S. troops landing on the beaches and advancing inland with great difficulty on the slippery, black volcanic sand.

The invasion fleet consisted of the three Marine divisions of about 70,000 men, around 450 naval ships of various types, as well as several thousand Navy Seabees. The Seabees were naval engineers who were experts at building roads and would be needed to open the island's three airfields.

Over five weeks of fierce fighting, the Marines suffered more than 25,000 casualties, including nearly 7,000 dead. The casualty rate was so high that the Army's 147th Infantry Regiment landed a month later to help with mopping-up operations.

The Japanese suffered even more devastating losses, with around 18,000 killed. Despite efforts to get the Japanese to surrender, only 216 were taken prisoner. The rest were listed as missing and presumed dead.

Sporadic fighting continued until the war ended on Aug. 15, 1945. However, two Japanese holdouts hid in the island's caves and tunnels until they finally surrendered in 1949.

One of the most iconic images of World War II was taken by The Associated Press photographer Joe Rosenthal. His photograph captured six Americans raising the U.S. flag on Iwo Jima on Feb. 23, 1945. Marine Sgt. Bill Genaust, who was standing beside Rosenthal, captured the same moment on video. Genaust was killed nine days later.

The image of the flag raising was so powerful that it was featured on a U.S. postage stamp, and a large statue of the flag raising is featured at the Marine Corps War Memorial in Arlington, Virginia.

Many books were written and movies made about the battle for Iwo Jima. Three of those films are the 1949 "Sands of Iwo Jima," starring actors John Wayne and Forrest Tucker, and two 2006 movies directed by Clint Eastwood: "Letters from Iwo Jima" and "Flags of Our Fathers."

The U.S. returned Iwo Jima to Japanese control in 1968. Today, the Japan Maritime, Ground and Air Self-Defense Forces maintain a presence on the island.

Japan is now one of America's most important allies.