Flags were normally converted inside the container; squaddies could add patches or symbols to represent victories or losses that

https://ericksigh824.birchreport.com/posts/the-uses-of-civil-war-flags-from-battlefields-to-museums-3

Flags have been frequently converted within the box; infantrymen may add patches or symbols to symbolize victories or losses that marked their unit's experience as a result of conflict.