Though the Allies didn't realize it until after the war, the Nagasaki atomic bombing was directed at a target capable of secrecy comparable to the Manhattan Project.

The primary military target for the bomb was Nagasaki's Mitsubishi Shipyard, a key cog in Japan's war machine.

It was a machine that produced the Musashi, crown jewel of Nagasaki's wartime ship-building operations and one of Japan's best-kept secrets.

The Musashi - then the biggest battleship in the world - was launched in 1940 in a crowded Nagasaki harbor.

And almost no one saw it - even citizens of the city.

The 868-foot-long, 128-foot-wide battleship carried nine huge guns and seven fighter planes. Construction began in 1937 at the Mitsubishi Shipyard, with the dock hidden behind curtains and metal sheets.

Before the hull was launched in November 1940, the Japanese built a tall, 330-foot-long wood warehouse between the harbor and the American and British consulates to block their view.

On Nov. 1, all harbor traffic was stopped. No one was allowed on any street or spot overlooking the harbor. People in homes facing the harbor had to close all curtains and shutters and stay inside.

Meanwhile, pairs of police officers visited every foreign home in Nagasaki at the same time, pretending to conduct a census.

Even the 1,800 police officers guarding the harbor were ordered to face away.

The Musashi was launched and taken to an island in the outer harbor for another 1 1/2 years of fitting. There, it was hidden behind a screen of ships.

The Americans sank the Musashi on Oct. 24, 1944, near the Philippines, killing 1,039 of the 2,339 sailors aboard.