Bill, Fort Monroe did not leave Union hands during the war. I refer to your sketch, numbered by line (1,2, etc.) and by column (A, B. C). With exceptions of 2C (indistinct), 4B, and 4C, these appear to be the conventional ("Rodgers") Navy Day ("flag hoist") Signals of the USN, used with modification by CSN. Both sides changed meanings for some of these at least once, so significance depends to some extent on which side was using the flag and when. The square "Star of David" (4C) and the three lozenges (4B) aren't part of that system, making me wonder if the young diarist misconstrued the design or the use. Tom Martin's Piedmont Flag Company web site (http://www.piedmontflag.com/Confederate-Navy-Signals.htm) has a beautiful color representation of initial CSN usage.)