army did not have sufficient shelter, doctors, or food for them. University of Connecticut Professor Jim Downs states that tens to hundreds of thousands of slaves died during the war from disease, starvation, or exposure and that if these deaths are counted in the war's total, the death toll would exceed 1 million. Losses were far higher than during the recent defeat of Mexico, which saw roughly thirteen thousand American deaths, including fewer than two thousand killed in battle, between 1846 and 1848. One reason for the high number of battle deaths during the war was the continued use of tactics similar to those of the Napoleonic Wars at the turn of the century, such as charging. With the advent of more accurate rifled barrels, Minié balls, and (near the end of the war for the Union army) repeating firearms such as the Spencer Repeating Rifle and the Henry Repeating Rifle, soldiers were mowed down when standing in lines in the open. This led to the adoption of trench warfare, a style of fighting that defined much of World War I. Emancipation Abolishing slavery was not a Union war goal from the outset, but it quickly became one. Lincoln's initial claims were that preserving the Union was the central goal of the war. In contrast, the South saw itself as fighting to preserve slavery. While not all Southerners saw themselves as fighting for slavery, most of the officers and over a third of the rank and file in Lee's army had close family ties to slavery. To Northerners, in contrast, the motivation was primarily to preserve the Union, not to abolish slavery. However, as the war dragged on, and it became clear that slavery was central to the conflict, and that emancipation was (to quote from the Emancipation Proclamation) "a fit and necessary war measure for suppressing [the] rebellion," Lincoln and his cabinet made ending slavery a war goal, culminating in the Emancipation Proclamation. Lincoln's decision to issue the Emancipation Proclamation angered both Peace Democrats ("Copperheads") and War Democrats, but energized most Republicans. By warning that free blacks would flood the North, Democrats made gains in the 1862 elections, but they did not gain control of Congress. The Republicans' counterargument that slavery was the mainstay of the enemy steadily gained support, with the Democrats losing decisively in the 1863 elections in the Northern state of Ohio when they tried to