As a historical artifact, Maryland's state song is an invaluable insight into the mindset of Maryland in 1861. We were a state awash in Southern sympathizers, and we looked none too kindly upon Abraham Lincoln and the Union Army.
It's not just a few anti-Lincoln references here or there in the nine-stanza poem set to "O Tannenbaum"; the song is a rallying cry to defend against "Northern scum." Those lyrics may be offensive by modern sensibilities (it's hard not to be a little taken aback when one of the nation's greatest presidents is referred to as a despot right off the bat), but they are part of our heritage.
That said, it's a shame there's no state song schoolchildren can proudly sing at school assemblies or other important events. Other states have them. No Kentucky Derby is complete without "My Old Kentucky Home" (which, ironically, has abolitionist roots). "Georgia On My Mind" is a good song for any occasion.
