A war-time photo of the 1st Minnesota flag carried at Gettysburg can be seen at:

http://www.1stminnesota.net/SearchResults.php3?ID=0428

Almost nothing of this flag survives today. However, an examination of a painting of this flag done by John Weide in 1896 indicates that the 1st Minnesota was carrying a Philadelphia Depot national flag in July 1863. This is also the conclusion of Bill Dalin as mentioned on his site:

http://www.regimentalcolors.net/pa6.html

Ryan Toews