Garry Owen (alternately known as Sergeant Flynn) is a folk song making extensive references to both the Seventh Calvary Regiment and their marching song, Garry Owen. The song details the cavalry charge at Custer's Last Stand, from the initial spotting of the Native enemy to the carnage after the fact.

I myself learned this song as a camper at a BSA summer camp, then promptly forgot it. When I became a counselor in training at the same camp I taught myself the song again, then forgot it as soon as my tenure was over. Once I was hired as a full-fledged staff member for the camp I took roughly a half-hour long shower, during which I forced myself to remember every damn word of this song. So it should come as no surprise that, for this writeup, I forgot the entirety of the second verse.

If it helps, I figure the beat of the song to be somewhere between 145-150 BPM. It very decidedly does not share a rhythym (or much of anything else) with the other song named Garry Owen. Unfortunately, this song is rare enough that there are - as far as I can tell - no recordings online of it being performed. 

Actually, an interesting note to make is that literally the only place I can find this song is in a single book (Rhymes for the Working Man) and on various websites dedicated to songs for Boy Scout programs. It's cool that there's a whole oral tradition hidden within the Scouts that has stayed relatively contained even during the Information Age. It's really cool that I get to be one of the first people to help destroy that containment.

The chorus is as follows:

Garry Owen, Garry Owen, Garry Owen (GARRY OWEN!)
In the valleys of Montana all alone (ALL ALONE!)
There are better days to be in the Seventh Cavalry
Then when charge again for dear old Garry Owen (GARRY OWEN!)

You can either start with a chorus (I do) or with the first verse. The song goes as follows:

VERSE 1:
I can hear the Sioux bucks singing Sergeant Flynn (SERGEANT FLYNN!)
And I can hear the tom-toms ringing Sergeant Flynn (SERGEANT FLYNN!)
I can hear the Sioux bucks singing
And I can hear the tom-toms ringing
But they don't yet know the tune to Garry Owen (GARRY OWEN!)

(CHORUS) 

VERSE 2:
Oh, it's the first call I hear sounding Sergeant Flynn (SERGEANT FLYNN!)
And it sounds like Taps a'rounding Sergeant Flynn (SERGEANT FLYNN!)
Look me lads, here's something fancy
Take a break, it's Private Clancy
You'll feel better when he strikes up Garry Owen (GARRY OWEN!)

(CHORUS)

VERSE 3:
For it's boots and saddles sounding Sergeant Flynn (SERGEANT FLYNN!)
Along the line your men are bounding Sergeant Flynn (SERGEANT FLYNN!)
So let's saddle up and fall in
For the trumpets are a-callin'
And the band is tuning up for Garry Owen (GARRY OWEN!)

(CHORUS)

VERSE 4: (the climax of the song)
Oh, it's forward we're advancing Sergeant Flynn (SERGEANT FLYNN!)
And the breeze guides are a'lancing Sergeant Flynn (SERGEANT FLYNN!)
Walk, trot, gallop, charge by thunder
WE WILL DRIVE THESE CUTTHROATS UNDER
Stab your sabers to the hilt for Garry Owen (GARRY OWEN!) 

(CHORUS)

VERSE 5: (sung slightly panicked)
We are ambushed and surrounded Sergeant Flynn (SERGEANT FLYNN!)
But retreat has not yet sounded Sergeant Flynn (SERGEANT FLYNN!)
Gather `round me men let's rally
MAKE OUR LAST STAND IN THIS VALLEY
For the seventh regiment and Garry Owen (GARRY OWEN!)

(CHORUS)

VERSE 6: (sung much slower and quieter until the last line)
We are cut and scalped and battered Sergeant Flynn (Sergeant Flynn)
All your men are dead and scattered Sergeant Flynn (Sergeant Flynn)
I will hang my head in sorrow
As I make your bed tomorrow
And over your grave, I'll whistle Taps
AND GARRY OWEN (GARRY OWEN!)

(CHORUS)