To my untrained eye those bottom figures look like early war US troops. That second figure on the right looks to me like he is wearing a "Smokey Bear" hat which was used at the outbreak of the war in the Pacific and was then used by drill instructors in both the Army and Marine Corps. But I could be wrong.
Robert Graves, the poet, describes a raiding party in his autobiography, "Goodbye to All That". They're armed with lead weighted coshes, hunting knives &, yes, sharpened entrenching tools.
Rifles are unwieldy in such circumstances & a man might be unwisely tempted to fire it, alerting the enemy. Only the officer leading the group would carry a revolver.
@Bluefalcion- Entrenching tool was more useful than bayonet because bayonet would stuck in soldiers chest, while using entrench tool you hit soldier on a shoulder and paralize his hand.