Until 1904, most ships that encountered trouble at sea effectively vanished. "Ships at sea out of visual range were very much isolated from shore and other ships," writes the Telegraph Office, an online history of Morse code. "A ship could vanish from the high seas, and no one would know until that vessel failed to make a port connection." But by 1904, many ships were equipped with some of the earliest wireless radios. For the first time, they could signal their distress, bringing help from the shore. A handful of distress codes was eventually whittled to one: three dots, three dashes, three dots. SOS.