From Andrew Kuntz's invaluable resource,  The Fiddler's Companion:

BATTLE OF THE SOMME, THE.  Scottish, Retreat March (9/8 time). D Major. Standard. AABB.  This pipe tune, a retreat from Army Manual (Book 2) and composed by William Laurie (1882-1916) commemorates one of the greatest and most terrible battles of World War I.  Jack Campin communicates that Laurie "just lived to see it become an immediate success before dying of his wounds a few months later."