CQD, transmitted in Morse code as – · – · – – · – – · · is one of the first distress signals adopted for radio use. It was announced on 7 January 1904, by "Circular 57" of the Marconi International Marine Communication Company, and became effective, beginning 1 February 1904 for Marconi installations.
Land telegraphs had traditionally used "CQ" (", from the French word ) 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. 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.
Although used worldwide by Marconi operators, CQD was never adopted as an international standard, since it could be mistaken for a general call "CQ" if the reception were poor. At the second International Radiotelegraphic Convention, held in Berlin in 1906, Germany's distress signal of three-dots/three-dashes/three-dots (· · · – – – · · · ) was adopted as the international Morse code distress signal. (This distress signal soon became known as " SOS". Germany had first adopted this distress signal in regulations effective 1 April 1905.)
Between 1899 and 1908, nine documented rescues were made by the use of wireless. The first distress call was simply "HELP". By February 1904, the Marconi Wireless Company required all of its operators to use CQD for a ship in distress or for requiring URGENT assistance. In the early morning of 23 January 1909, whilst sailing into New York from Liverpool, RMS Republic collided with the Italian liner SS Florida in fog off the island of Nantucket, Massachusetts, United States. Radio Operator Jack Binns sent the CQD distress signal by wireless transmission. This was the most famous use and rescue using wireless prior to that of the RMS Titanic.
In April 1912, RMS Titanic radio operator Jack Phillips initially sent "CQD", which was still commonly used by British ships. Harold Bride, the junior radio operator, jokingly suggested using the new code, "SOS". Thinking it might be the only time he would get to use it, Phillips began to alternate between the two.