I saw this on The Genealogist recently – Using Regimental Histories to discover your ancestor’s war – First World War Regimental histories can reveal some fascinating details for family historians tracing their ancestors in World War I: https://www.thegenealogist.co.uk/featuredarticles/2019/using-regimental-histories-to-discover-your-ancestors-war-1187/
These publications often provide details of battles and campaigns that the regiments were involved in and also lists the officers, and in some cases the men. They typically include various details relating to honours and medals awarded in the conflict. These military histories concentrate on a particular regiment, battalion or division and typically give a good account of the men’s progress across the battlefield usually including maps for better understanding the geography.
Most of these narratives will also name men and officers who had distinguished themselves on the battlefield and so if your soldier ancestor had been involved in some action at the time, that deserved a mention, then these records could fill in the story of their war for you.