Coordinated Defense is available for research at a level 5 or above Barracks. It gives troops trained at that city an increase to their maximum hitpoints when defending, while reducing their travel speed when reinforcing. Although the description states "Defensive Reinforcement Troops" the hitpoint increase applies any time they are defending including "Idle" troops defending their home city. Both percentages stack additively, and can be researched independently at multiple Barracks. Exact percentages can be found at the database link below.

Database reference