The 1863, G.O. 10, the HQ flags measurements were 2x6’. The Greek Cross was the Corps Badge of the 6th Corps. The badge was ordered to be worn upright, but it appeared as a saltire on several surviving HQ flags carried by the 6th Corps starting in 1864, (size 3x6’). The 3rd Division flags, it appears, had the Greek Cross, the flags of the other divisions had a saltire.

The St. Andrews Cross is on the flag of Scotland. The saltire is mistakenly called a St. Andrews Cross on these flags.

Happy Trails!
Tom Martin