Implement a system that allows DoL/DoH to contribute to the "ecosystem/environment" of Eureka. Get various DoH jobs to build specifix things like fortifications or tents (they're not permanent on the field). Have DoL gather supplies for the DoH people or special "coatings/ammunition" for DoW/DoM. Have rewards set on a weekly basis and incremental in regards to how much you get done with the three overall disciplines.

Eureka is a land of massively untapped potential. There's so much content that could be added onto it, its stoopid.