What Does SOS Stand For? Nothing, and Marconi Said So

“S.O.S. is, I am told, ‘Save our souls.’” The Attorney-General said it to Guglielmo Marconi, whose company staffed the Titanic’s wireless room, at the British inquiry into the disaster on 18 June 1912, and asked whether it was “simply an easy way to remember it”. Marconi replied, “That is so.”

Two questions earlier, the Wreck Commissioner, Lord Mersey, had asked him outright: “What does S.O.S. stand for, anything, or is it simply three letters?” Marconi’s answer, in the inquiry transcript, was “Simply three letters, My Lord.”

What does SOS stand for?

SOS does not stand for anything. It is a Morse rhythm, three dots, three dashes and three dots sent unbroken, and Etymonline says it was chosen as “easy to transmit and difficult to mistake.” The 1906 Berlin treaty that adopted it prescribes only the dots and dashes, never the letters. Save Our Souls and Save Our Ship are later memory aids.

The treaty gives a rhythm and no letters

The rhythm entered the rulebooks in Germany. Wireless regulations in force from 1 April 1905 kept “ordinary Morse signals” and listed a distress signal, the Notzeichen, written ...---..., among the “additional signals”, as The Electrician reported that May.

The Berlin conference adopted the same signal for every signatory, in a convention signed on 3 November 1906 that took effect on 1 July 1908. Regulation XVI reads: “Ships in distress shall use the following signal: ...---... repeated at brief intervals.” The letters S, O and S appear nowhere in the treaty.

The letters appear only when the rhythm is cut into three groups. In International Morse, as the ITU still tabulates it, three dots are S and three dashes are O, and ordinary Morse leaves a gap of three dot-lengths between letters. The distress signal is keyed straight through, and Thomas H. White, whose Early Radio History site hosts these texts, glosses it in a note to The Electrician’s 1905 report as “three-dots/three-dashes/three-dots all run together, and not really the three separate letters” SOS.

Many American operators called it S5S

The letters also depended on which Morse an operator knew. Many American coastal ships worked in American Morse, which was based on the codes of the landline telegraph, and in it three dashes make the figure 5. Landline operators had a look-alike problem of their own: in the same code, Z was often confused with the letter pair SE, and that mix-up is one clue in the argument over the keyboard’s letter order.

When the Lake Michigan steamer Puritan lost her rudder in a heavy sea, Popular Mechanics reported in February 1910 that “S 5 S” was the message that went out, and called it “the American code signal of distress.”

In 1910 one distress call had two spellings, SOS in International Morse and S5S in American Morse. Popular Mechanics told its readers the combination “has no special significance, being merely a succession of dots and dashes quickly made and easily recognized.”

CQD collected an invented expansion too

The call that SOS displaced has the same kind of folklore attached. Marconi’s company issued Circular 57 on 7 January 1904: the general call “C.Q.” (All Stations) “does not sufficiently express the urgency required in a signal of distress”, so from 1 February ships in trouble would send “C.Q.D.” instead, and misuse meant “instant dismissal.”

Reprinting the circular in The Yearbook of Wireless Telegraphy and Telephony for 1913, G.E. Turnbull explained that the D was added “denoting ‘Distress’” and wrote that “probably the most amusing explanation of the signal was that it indicated ‘Come Quick, Danger.’”

Popular Mechanics had printed that expansion as fact in its 1910 S5S article, and when Lord Mersey put it to Marconi in 1912, Marconi allowed that CQD “can be interpreted that way.” Other short codes collect origin stories the same way: the police nickname 12 has four in circulation and no dated first use behind any of them.

The Titanic did not send the first SOS

The Titanic often gets the credit for the first SOS, but the call was on the air nearly three years earlier. Modern Electrics noted that when the Cunard liner Slavonia was wrecked off the Azores on 10 June 1909, two steamers received her “S. O. S” and went to her rescue. On 11 August 1909 Theodore Haubner, the Arapahoe’s operator off Cape Hatteras, was unsure which call to use and sent both, the first recorded American use of SOS.

The Titanic opened with CQD. Harold Bride, the junior operator, told the New York Times that Phillips, the senior operator, was sending “C.Q.D.” when Bride cut in with a joke: “Send ‘S.O.S.,’ I said, ‘it’s the new call, and it may be your last chance to send it.’” The “new call” had been the treaty signal for almost four years.

Four months after the sinking, the Radio Act of 13 August 1912 put the rhythm into US statute as “the international signal of distress ...---...”, with a fine of up to $2,500, up to five years in prison, or both, for a false distress call.

Mayday joined SOS as the spoken call

The idea that SOS was changed to Mayday mixes up two channels, Morse and voice. Etymonline records that mayday was chosen in early 1923 “at a meeting in London of representatives of the leading European aircraft manufacturing countries”, because it sounds like the French for help me.

The 1927 Washington radio regulations then set both in Article 19. “The distress signal consists of the group” of three dots, three dashes and three dots, while the radiotelephone distress call “consists of the spoken expression MAYDAY”, tied in the text to the French pronunciation of m’aider.

Morse radiotelegraphy kept its place as ships’ required distress system until 1 February 1999, when the Global Maritime Distress and Safety System became fully operational and, in the International Maritime Organization’s words, “the Morse Code was phased out.” The rhythm itself survives: the international collision rules still list the group ...---... (SOS), made “by any signaling method”, as a distress signal, next to the spoken word “Mayday”.

Call	First rule	Medium	What it means
CQD	Marconi Circular 57, 1904	Morse, Marconi operators	CQ, all stations, plus D for distress
SOS	German rules 1905, Berlin treaty 1906	Morse, treaty signatories	Nothing
MAYDAY	London meeting 1923, Washington rules 1927	Voice radio	The French m’aider, help me

Phones and texts borrowed the letters

The SOS of a text message is the figurative sense, “urgent appeal for help”, which Etymonline dates to 1918. On some phones, “SOS” or “SOS only” in the status bar means the device “isn’t connected to your cellular network, but you can still make emergency calls through other carrier networks,” as one manufacturer’s support page puts it.

Asked at the 1912 inquiry why SOS had been adopted, Marconi answered: “I really cannot say. I think C.Q.D. is just as good, but they wanted to make a change.” Strictly FYI.