The Submarines that Hunted Pirates

For nearly a century, the waters surrounding the British colony of Hong Kong—and most of the South China Sea, for that matter—were plagued by piracy. Over the decades, numerous pirate leaders made their way into the history books because of their ruthlessness and cruelty. But in the 1920s, the British Royal Navy put a new secret weapon to the test to combat the threat.

By the early twentieth century, pirates in the Pearl River Delta had evolved into highly organised, mobile syndicates. Whenever a heavily armed Royal Navy warship left port, the pirates would be tipped off, enabling them to vanish into coastal inlets that were inaccessible to the larger British vessels.

To prevent the movements of their surface ships from being spotted, the British deployed their L-class submarines. In October 1927, the submarines HMS L4 and HMS L5 slipped out of Victoria Harbour under the guise of routine training exercises. Instead, they sailed straight for Bias Bay, a notorious pirate stronghold.

Days after the two submarines departed, a Chinese merchant steamer, the SS Irene, was hijacked by Bias Bay pirates. In the dead of night on October 19, 1927, HMS L4 intercepted the captured vessel. When the SS Irene ignored commands to stop, the submarine fired warning shots, followed by live shells into the steamer’s engine room, forcing it to a halt.

Although the steamer ultimately sank, the submarine crew successfully surprised the pirates, rescued most of the passengers, and brought the hijackers to justice in Hong Kong. In fact, these tactics proved so effective that the strategy was maintained well into the 1930s.