This is what a broom tied to a mast means in the U.S. Navy

When the USS Wahoo sailed into Pear Harbor on Feb. 7, 1943, she had an odd ornament on her periscope: a common broom. But that broom was one of the most impressive symbols a crew could aspire to earn because it symbolized that the boat had destroyed an entire enemy convoy, sweeping it from the seas.

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Historians aren't certain where the tradition originated, but the story cited most often was that a Dutch admiral in the 1650s began the practice after sweeping the British from the seas at the Battle of Dungeness.

(Video: YouTube/Smithsonian Channel)

For the crew of the Wahoo, their great victory came in the middle of five tense days of fighting. It all began on Jan. 24 when the sub was mapping a forward Japanese base on a small island near Papua New Guinea. During the reconnaissance mission, the sailors spotted a destroyer in the water.

Flush with torpedoes and no other threats in sight, the Wahoo decided to engage. It fired a spread of three torpedoes but had underestimated the destroyer's speed. The Wahoo fired another torpedo with the speed taken into account, but the destroyer turned out of the weapon's path.

And then it bore down on the Wahoo, seeking to destroy the American sub. The crew played a high-stakes game of chicken by holding the sub in position. When the destroyer reached 1,200 yards, the crew fired the fifth torpedo, which the destroyer again avoided.

At 800 yards they fired their sixth and last forward torpedo, barely enough range for the torpedo to arm. The risk of failure was so great that Lt. Cmdr. Dudley Morton ordered a crash dive immediately after firing, putting as much water in the way of enemy depth charges as possible.

But the last torpedo swam true and hit the Japanese ship in the middle, breaking its keel and causing its boilers to burst.

The next day, Jan. 25, was relatively uneventful, but Jan. 26 would be the Wahoo's date with destiny. Just over an hour after sunrise, the third officer spotted smoke over the horizon and Morton ordered an intercept course.

They found a four-ship convoy consisting of a tanker, a troop transport, and two freighters. All four were valuable targets, but sinking the troop transport could save thousands of lives and sinking tankers would slow the Japanese war machine by starving ships of fuel.

There was no escort, but the Wahoo still had to watch for enemy deck guns and ramming maneuvers. The sub fired a four-torpedo spread at the two freighters, scoring three hits. The first target sank and the second was wounded. Wahoo then turned its attention to the tanker and the troop transport.

The troop transport attempted a ram, sailing straight at the Wahoo. Morton ordered a risky gambit, firing a torpedo at the transport after it drew close rather than taking evasive actions.

After the torpedo was launched, the transport took its own evasive action and abandoned its ramming maneuver. In doing so, the transport presented the sub with its broad sides, a prime target.

The Wahoo fired two more torpedoes and dove to avoid another attack. It was still diving when both torpedoes struck home. Eight minutes later, the Wahoo surfaced and saw that the transport was dead in the water. It fired a torpedo that failed to detonate and then a carefully aimed final shot that triggered a massive explosion and doomed the Japanese vessel.

As the tanker and the damaged freighter attempted to escape, Morton gave the controversial order to sink all manned boats launched from the dying transport. His rationale was that a manned, seaworthy vessel was a legal target and any survivors of the battle would go on to kill American soldiers and Marines during land battles.

A few hours later, the Wahoo was able to find and re-engage the two survivors of her earlier action. The tanker and the wounded freighter had steamed north but couldn't move fast enough to escape the American sub.

The Wahoo waited for nightfall and then fired two torpedoes at the undamaged tanker. One hit, but the ship was still able to sail quickly. With only four torpedoes left and the Japanese ships taking evasive action, Wahoo waited and studied their movements.

When certain they could predict the Japanese ships, the crew attacked again. The first pair of torpedoes were fired at the tanker just after it turned. One of them slammed into its middle, breaking the keel and quickly sending it to the depths.

The crippled freighter was firing what weapons it had at the sub and almost hit it with a shell, forcing it to dive. Then, a searchlight appeared from over the horizon, possibly signaling a Japanese warship that could save the freighter.

The Wahoo carefully lined up its final shot at 2,900 and fired both torpedoes at once with no spread, a sort of final Hail-Mary to try and sink the freighter before it could find safety with the warship.

The final pair of torpedoes both hit, their warheads tearing open the freighter and quickly sinking it before the Japanese ship, which turned out to be a destroyer, cleared the horizon.

The American crew escaped and continued their patrol, attempting to attack another convoy with just their deck guns on Jan. 27 and mapping a Japanese explosives facility on Jan. 28 before returning to Pearl Harbor with the triumphant broom flying high on Feb. 7.

Other ships have used brooms to symbolize great success, such as in 2003 when the USS Cheyenne flew one to celebrate that every Tomahawk it launched in Operation Iraqi Freedom landing on target with zero duds or failures.