Chapter 4 examines partisan war participation differences using soldier voting tallies and county-level data on soldier service records linked with election data to test party differences in local military enlistment, desertion, and death. Soldiers in the field voted more for Republicans than did civilians back home. Likewise, Republican places contributed a larger share of local men to fight, those men were less likely to desert once in the ranks, and they were more likely to die in service. Democratic places were less willing to shoulder the mortal burdens of war to preserve the Union by suppressing the assault from their former partisan brethren. Thus, parties substantially organized the war service of their followers beyond the mobilizing power of government. Changes in partisan enlistment gaps over time follow shifts in partisan news support for war – striking evidence of dynamic leadership. Chapter 4 also finds some local partisan influence on African American enlistment and describes women’s war service. In sum, partisanship motivated ordinary Republicans more to save the Union through violent action, even as Democratic partisanship impeded the war.