Slitherine

After starting in 1915 with the Entente Allies, I invaded, and surprisingly took Gallipoli! Before I keep up the offensive, how does supplying work, must I keep a unit near the Warship? My first objective is to capture Constantinople, but if I start having supply trouble, I might as well kiss it goodbye!

For the present you have to keep a surface warship adjacent to land units for them to maintain full supply, units that that have connecting captured hexes to Galipoli stay at half supply until Turkish capital is captured, then all your units will be at full supply. It helps to capture remaining Galipoli canal hex so that your ships can enter to bring units full supply further away from fort.