If you passed, came out, or came through, “with flying colors,” you succeeded with distinction, were triumphant or victorious. “Sailing under false colours,” on the other hand, means practicing deception or being misleading.
Both phrases are nautical, related to ship flags, also known as “colors.”
In the past, when we did not have modern communication devices, a ship’s appearance on returning to port could signal how the crew had fared at sea. Ships that were victorious in their endeavors would sail into port with flags flying from the mastheads. But, a ship that had been defeated would be forced to “strike her colors,” or to take them down, signifying her defeat. In which case, she probably didn’t return to home port!
Although the phrases began as nautical language, they were soon used figuratively to signify any kind of triumph. Another phrase, “go down with flying colors,” meant that a crew fought until their ship sank. A variant of this phrase is, “Nail your colors to the mast.” If the flag was nailed onto the mast, it couldn’t be lowered, which meant the crew would not surrender.
Colors, or flags, were used to display allegiance to a nation or company. “Flying,” of course, refers to the unfurled flags’ position on the masthead.
Similarly, the phrase “sailing under false colors” was a reference to a tactic used by pirates to attack vessels to gain booty. If the pirates flew a friendly flag, the unsuspecting victim would allow the pirates’ ship to approach, giving them the chance to board and overcome the crew. Blackbeard famously repeated this process for two years.
Pirates preyed on commerce from the times of the ancient Phoenicians and Greeks until about 1825, when a concerted effort by the US and Britain finally destroyed their last North African, European, and West Indian strongholds.
The term “false colors” began to be used figuratively by 1700 or even earlier, according to Fighting Words: From War, Rebellion, and other Combative Capers by Christine Ammer. Robert Louis Stevenson wrote, “I had so much wisdom as to sail under false colours.”
These days, we’re more likely to use the phrase when we’ve passed an exam or got a better job. Or, for me, when I’ve succeeded in remembering to change every clock in the house when fickle time leaps forward or falls back.