Among these web pages are Piping Traditions, especially those associated with the American Civil War (which aren't many). Further stories and background involve the Cameron Highlanders of the British Army and other Scottish units, and those associated or patterned after them.
Piper Kenneth MacKay, of the 79th Cameron Highlanders, at the Battle of Quatre Bras,
Belgium, two days before the Battle of Waterloo, in June 1815. As the regiment was
formed in a square to resist and repel a cavalry attack, MacKay inspires his fellow soldiers
by pipingthe famous "battle piobaireachd," Cogadh na Sith ("War or Peace"),
outside of the protection of the square.
NEFA, The North East Folklore Archive, is a cultural resource created for the study and appreciation of the traditions and social history of Aberdeenshire. Their article, Bagpipes in War, is a really good one.
Also noteworthy is, A Piper's Notes - David Low discusses Henderson's bagpipe music books--which goes into some detail in pipe music of the 1800s (especially pre-1847)