Sonar

“The sea is everything.” — Jules Verne

Sonar — the detection of objects underwater using sound waves — opened the hidden depths of the ocean to human awareness. Originally developed to counter the submarine threat, it gave naval forces the ability to hunt beneath the waves and protect surface fleets from unseen attack.

Unlocks

• Units: Destroyer

Historical Background

The principles behind sonar were understood long before the technology was developed. Leonardo da Vinci noted in 1490 that sound could be detected through water by pressing an ear to a submerged tube. However, practical underwater detection systems were not developed until the early 20th century, spurred by two catalysts: the sinking of the Titanic by an iceberg in 1912 and the devastating effectiveness of German U-boats during the First World War.

The first active sonar systems (originally called ASDIC by the British) were developed during and after World War I, using piezoelectric transducers to emit sound pulses and detect their echoes. By World War II, sonar had become essential to anti-submarine warfare. Destroyers — fast, agile warships equipped with sonar and depth charges — became the primary hunters of submarines. The Battle of the Atlantic, the longest continuous campaign of the Second World War, was fundamentally a contest between submarine stealth and sonar detection. The technology continues to evolve, remaining central to naval warfare and oceanographic research alike.