I read the book by Harold G Moore this year in Peru and it is a sign of how good a book is that in one moment you can be transported back to the vivid horror of the battle of Ia Drang and the bravery of the Americans in the 7th Cavalry Regiment.
There are repeated references to 'garryowen'. The soldiers whould shout 'garryowen' when they charged against the enemy and I only discovered today by chance that Garry Owen is an Irish 'air' and the quickmarch of the Ulster Defence Regiment (UDR). The song originated with the lager louts of Limerick in the 18th century and I very much doubt that the Viet cong understood what the Americans were shouting at them when they attacked(!).
I found the following video
The lyrics are as follows:
Let Bacchus' sons be not dismayed
But join with me, each jovial blade
Come, drink and sing and lend your aid
To help me with the chorus:
cho: Instead of spa, we'll drink brown ale
And pay the reckoning on the nail;
No man for debt shall go to jail
From Garryowen in glory.
We'll beat the bailiffs out of fun,
We'll make the mayor and sheriffs run
We are the boys no man dares dun
If he regards a whole skin.
Our hearts so stout have got no fame
For soon 'tis known from whence we came
Where'er we go they fear the name
Of Garryowen in glory.