GDG- (no subject)

[Smith, David]

I haven't posted in a while, so here's a question that has been
bothering me.
 
What is up with Civil War officer ranks, North and South?  Lee creates
Lieutenant Generals for his corps commanders.  Richard McMurry, in Two
Great Armies, says its hard to find a bio of anyone less than a
lieutenant general in the western armies (there are a few).
 
Meanwhile, at Gettysburg, Lee and his lieutenant generals are defeated
by George Gordon Meade, a lowly (in comparison) major general.  Meade
had commanded a corps for some time before Gettysburg, but in Lee's
army, it seems unusual to command a corps at that rank.
 
Why the difference between Confederate and Union ranks?
 
David