CQD

CQD was was established as the official distress call in 1904 on today's date. Two years later it would be replaced with SOS.

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From Wikipedia

Land telegraphs had traditionally used "CQ" ("sécu", from the French word sécurité)^[2] to identify alert or precautionary messages of interest to all stations along a telegraph line, and CQ had also been adopted as a "general call" for maritime radio use. However, in landline usage there was no general emergency signal, so the Marconi company added a "D" ("distress") to CQ in order to create its distress call. Sending "D" was already used internationally to indicate an urgent message. Thus, "CQD" is understood by wireless operators to mean, "All stations: distress." Contrary to popular belief, CQD does not stand for "Come Quick, Danger", "Come Quickly: Distress", "Come Quick – Drowning!", or "C Q Danger" ("Seek You, Danger"); these are backronyms.

 On April 15, 1912, RMS Titanic radio operator Jack Phillips initially sent "CQD", which was still commonly used by British ships. Harold Bride, the junior radio operator, suggested using "SOS", saying half-jokingly that it might be his last chance to use the new code. Phillips thereafter began to alternate between the two.^[9] Though Bride survived the sinking, Phillips did not.^[10]