This is the note to the song from Georges-Denis Zimmermann's Songs of Irish Rebellion

"VARIANTS A: A version in Harding's Songs, Ballads, and Poetry of Ire¬land, p. 42, gives a chorus:

At the risin' of the moon,
At the risin' of the moon,
For the pikes must be together
At the risin' of the moon.

B. Most song books reprint a slightly different version first published in 1866 in Casey's Wreath of Shamrocks, pp. 31-33.
TUNE: «The Wearing of the Green», (cf. song 21).

NOTE: Unlike «The Saxon Shilling», «The Memory of the Dead», and «Patrick Sheehan» (songs 49, 57 and 63), it seems that this ballad was cir¬culated on broadsides before appearing in newspapers and song books. Eugene Davis says that Casey had for some time the idea of writing bal¬lads to be sold at the country fairs and markets; one thousand copies of «The Rising of the Moon» would have circulated in Longford, Cavan and Westmeath before Casey settled in Dublin, c. 1865. (See biographical in¬troduction to Reliques of John K. Casey, p. 51.) This is confirmed by an anonymous review of A Wreath of Shamrocks in The Nation, 23rd Fe¬bruary, 1867: «Many of the pieces which it contains have ere now made their appearance on ballad slips . .. His 'Rising of the Moon' is well known in some of qur midland counties, and admired, except by the 'authori¬ties' . . .1)
This is of course the ballad which inspired Lady Gregory's one-act play with the same title."
I assume your "The Reliques of John K Casey (Leo)' is the same as ours entitled 'The Rising of the Moon', Martin
Well worth searching out for the excellent introductory essay on both the composer and the period
Jim Carroll