Definition of "soldiering"

Thus the two comrades came back from their soldierings to their humble homes, from which Lincoln was soon to start on the way marked out for him by Providence, with strides which no comrade, with whatever goodwill, might hope to follow.

1914, John George Nicolay, Abraham Lincoln: A History, volume 1

All modern armies rely on veritable fleets of drones for routine soldiering (static garrisons, patrols, etc.).

2008, BioWare, Mass Effect (Science Fiction), Redwood City: Electronic Arts, PC, scene: Vehicles: Combat Drones Codex entry