Though limited to the Union perspective, an upcoming 2017 study along this vein is Steven E. Sodergren's The Army of the Potomac in the Overland and Petersburg Campaigns: Union Soldiers and Trench Warfare, 1864-1865 (LSU Press, June 2017). In it, he "examines the transition to trench warfare, the lengthy campaigns of attrition that resulted, and how these seemingly grim new realities affected the mindset and morale of Union soldiers." Though the mass casualties suffered during the Overland Campaign negatively impacted the physical condition of the Army of the Potomac and the spirit and morale of the men in the ranks, the more fixed nature of the Petersburg front combined with the protection afforded by miles of earthworks led to a "physically and psychologically regenerative" experience for the boys in blue, one that would propel the army to breakthrough and victory in 1865.
More from the description: "Comprehending that the extensive fortification network surrounding them benefited their survival, soldiers quickly adjusted to life in the trenches despite the harsh conditions. The army’s static position allowed the Union logistical structure to supply the front lines with much-needed resources like food and mail—even a few luxuries. The elevated morale that resulted, combined with the reelection of Abraham Lincoln in November 1864 and the increasing number of deserters from the Confederate lines, only confirmed the growing belief among the soldiers in the trenches that Union victory was inevitable. Taken together, these aspects of the Petersburg experience mitigated the negative effects of trench warfare and allowed men to adapt more easily to their new world of combat."