Following the official version of events, the "incident" occurred. In the United States Navy, the USS O'Bannon served as a destroyer during both World War II and the Korean War. On the evening of April 4, 1943, she was a part of Destroyer Squadron TWENTY-ONE (DesRon 21), which shelled Japanese bases in the New Georgia area. The O'Bannon's arsenal was impressive by any measure, including anti-aircraft guns, torpedo tubes for both surface and underwater targets, and five 5"/38 caliber guns for use on land. Few threats existed that this ship, or one like it, couldn't overcome. 

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The crew of the O'Bannon encountered one such, in the April of 1943, while stationed in the Pacific. While returning to base in Nouméa, New Caledonia, the O'Bannon spotted the Ro-34, a large Japanese submarine early the following morning. Commander Edwin R. Wilkinson of the O'Bannon gave the order to speed up and ram the submarine as it was cruising on the surface seemingly oblivious to the approaching American ship.

However, as they drew closer, they slowed down to a more manageable pace to be on the safe side. Could it have been planting mines? Since the explosion would completely wipe out the destroyer, ramming it would be a suicidal move.

The O'Bannon avoided a collision by making a sharp turn and eventually found itself cruising alongside the target ship (which, it turned out, wasn't laying mines). Silence settled in as the two sides ogled each other, uncertain of what to do next, according to Ernest A. Herr (who was on the O'Bannon that day). Evidently, the military's standard operating procedure didn't apply in this case. A time came when the Japanese attempted to shoot down the O'Bannon by activating their surface gun.

The Japanese had laid a trap for the Americans. Though the O'Bannon was armed to the teeth, it was helpless because none of its weapons were suitable for close quarters combat. Those 5” /38 guns were capable of hitting targets up to ten or twenty football fields away, they were completely ineffective at closer ranges.

O'Bannon's crew didn't want to shoot at the Japanese submariners because they were unarmed and prepared for close combat. When they couldn't think of what to do, the sailors looked around for anything that could be used as a weapon. Luckily, there was a large stock of potatoes not far away. In a last-ditch effort to distract the Japanese from their deck gun, the crew reached in and threw as many as they could at the enemy below. They were totally wrong about that. 

Among the Japanese submarine crew, there was widespread fear and panic. Some of the braver ones took the potatoes and threw them overboard. Many people returned them to the Americans, who handed them back to the Japanese.It took some time for the Americans to figure out that the Japanese had panicked because they had mistaken the potatoes for hand grenades. Herr has no idea why the Japanese were so afraid of the potatoes, but he is very appreciative that they were. 

Meanwhile, the O'Bannon managed to separate itself from the submarine because of the ensuing potato war. It waited until it was safe to do so before firing its deck guns at the Ro-34, destroying its conning tower. Japanese submarine dove, so destroyer sped up again, swooping over head to fire depth charges that eventually sank the sub. 

Because of this, the 300 American survivors are still here today. O'Bannon was the recipient of a plaque commemorating the incident from the Maine Potato Growers Association. The plaque read "A celebration of the spring 1943 success of the officers and crew of the USS O'Bannon in "sinking" a Japanese submarine with a potato. Potato Growers of Maine, June 14, 1943.” 

After serving in the Korean War, the ship was decommissioned in 1970, but this plaque remained on board until then. In another version of this strange event, the cooks were peeling potatoes when the submarine surfaced so close that they threw the potatoes at it. According to later accounts, the O'Bannon rammed the sub, causing it to sink. They say the submarine sank because the hatches weren't closed tightly enough, allowing too much water inside.