I may be incorrect in this (those with more and better knowledge of the topic please correct me), but as I understand it: In Signalling via flag, Instructions or Orders to individual ships are flown from the Port foremost yardarm, whereas Instructions or Orders to the entire Squadron or Fleet are flown from the foremost Starboard yardarm.
This was the case in the Royal Navy up to and including WW2, and I have no reason to believe the US Navy would have been very different in this in the preceding century.
Corey, it is really good to see you designing and building again My Friend.
Kind and Respectful Regards, Uyraell.