The Combat Resolution Step of the Combat Phase from ESR Second Edition has been replaced with the Threat Step.
Threat in the Combat Phase
ESR Series 3 introduces a unified Threat Assessment mechanic that is used in both the Movement Phase (replacing Artillery & Skirmishing) and in the Combat Phase. What differs between them is that ranged Infantry Threat, i.e. skirmishing, is only considered during the Movement Phase, while in the Combat Phase Infantry and Cavalry at contact factor in.
Batch Unit Combat Resolution
Unlike in ESR Second Edition where players roll for each individual Unit-level Combat Resolution, in ESR Series 3 Threat Assessment is performed in a batch process where two opposing Formations add up their respective circumstantial factors and compare them. The results are then applied at the Formation level, but still have implications for individual Units.