Flags were often times used as rallying issues in the course of battles; soldiers would acquire around their colours for morale

https://johnathanxqgy357.inkharbory.com/posts/the-legacy-of-civil-war-flags-symbolism-and-design-throughout-history-2

Flags had been occasionally used as rallying issues in the time of battles; squaddies would collect around their colours for morale enhance whilst confronted with overwhelming odds.