When a ship could take no more, a signal flag would be raised.
From the charlotteobserver.com
It can be traced back to 1823 when it was created as a signal flag, never intended as a civil jack.
From the en.wikipedia.org
Although not an official national flag, the Z signal flag played a major role in Japanese naval history.
From the en.wikipedia.org
Reenactments of a recruitment drive and enlistment ceremony, with unit drills and signal-flag and weapons demonstrations.
From the washingtonpost.com
Once aboard Monssen, Puller and the destroyer led 10 landing craft towards Point Cruz and established communications with Kelly on the ridge by signal flag.
From the en.wikipedia.org
Flying from the stairway in the dark was an upside-down flag, a signal of distress.
From the huffingtonpost.com
The assistant referee had not raised his flag to signal an offside call.
From the washingtonpost.com
Lowe was to give flag signal directions to the artillery who would fire blindly on Falls Church.
From the en.wikipedia.org
Using touch-screen computers, visitors can learn to recognize bugle calls, decode signal corps flag messages and locate battlefield monuments.