Very surprisingly, the earliest known mention of the title "Garryowen," more or less, appears to be in the United States.

The March 21, 1799, issue of the "Aurora [Pa.] General Advertiser" describes a St. Patrick's Day celebration in Philadelphia held on the 18th. The music played included "Patrick's Day in the Morning," "Erin g' Bragh [sic]," "Kouleen [sic]," "Battle of Aughrim," "Rights of Man," "The Girl I Left Behind Me," and "Garry O Na' Glorah."

If the last isn't "Garryowen in Glory," what is it?

Almost as remarkable is the mention, in the La Harpe, Ill. "La Harper" (May 28, 1886) of the evidently identical "Garry O'er Na Gloria."

Most interesting is that the (faux-Irish?) title 'Garry O Na' Glorah" seems to suggest that the familiar lyrics as well as the tune were known in the U.S. as early as 1799.