The description for Mass Battle Toolkit is very accurate as to what it's for, providing tables for generating situations, an easy-to-use system for unit combat, and how players can affect the battle in a quantifiable way.

Toolkit for running large-scale battles. Can be run as: (i) a series of PC actions; (ii) simple large unit combats; (iii) a mixture of both. Builds on similar ideas used in the same author's (very good) Battle for Rivertop; there is plenty of variety in how the action may unfold. A strength is that you can pick and choose which parts to use whilst maintaining the coherence of the whole. I advise running a few trials to calibrate a sensible number of opponents for the PCs in the Party Spotlight phases.

Recommended.