By 1864, Georgia had become the most important cog in the Confederacy's war machine. The state's factories and farms supplied Rebel armies in the field.
In Atlanta, military department workers filled downtown buildings, and its industries churned out uniforms, ammunition and train rails. In three years the population had doubled to 20,000, and fully one-fourth of residents had war-related jobs.
Most importantly, all of Georgia's vast war production was linked by a railroad network in which Atlanta was the hub. For the Union, cutting the South's critical supply lines meant capturing Atlanta.
There were political implications to that goal as well. In the North, Lincoln’s 1864 reelection campaign had become a referendum on the war itself. The Democrats were calling for peace talks, and their message that white Unionists shouldn't die for the emancipation of slaves found many sympathetic ears. Other Northerners had doubts whether the war was winnable at all.
As summer approached, many believed Lincoln would lose the White House unless the Union won a major military victory before the fall election.
The names of the trains have changed and more railroads have built into the city in the 150 years since, but Atlanta’s core rail network follows the same roadbeds that were in place during the Civil War. The Gulch in the heart of downtown remains a focal point of rail traffic through the city.
As both armies reached Fulton County, casualties and the need to assign troops to guard Union supply lines had lowered Sherman's advantage in men over Johnston to 8-to-5. Still, when Union forces followed the retreating Confederates across the Chattahoochee River, the Southerners were backed up to Atlanta.
On July 17, a nervous Confederate government replaced Johnston as commander. His successor, John Bell Hood, had Atlanta's defensive network as an advantage. But Hood was ready to take the fight to the enemy.
By mid-July, combat was no longer something Atlantans just read about in newspapers. It was here.
The city's defensive works -- which the Confederates had spent a year constructing using the forced labor of thousands of slaves -- were massive, and completely encircled the city. Sherman knew better than to attack head on. Instead, he sought to cut the railroads that kept Hood's army supplied. Meanwhile, Atlanta's population shrank below pre-war levels in a matter of weeks as thousands fled to safer points.
On July 20, Union cannons reached a position where shells could hit Downtown. For the next 36 days, homes, stores and streets were bombarded. Fortunately, a reduced civilian population meant the number of non-combatants killed (around 25) was much smaller than it could have been.
Coincidentally, the first shells started falling on the same day the fight for Atlanta would begin in earnest. Over the next six weeks, five battles would change history.
For 36 consecutive days, Union armies besieging Atlanta rained cannon shells into the city. Stephen Davis, author of the book “What the Yankees Did to Us: Sherman’s Bombardment and Wrecking of Atlanta,” researched Union artillery records, Southern newspapers and other sources to determine how many shells were fired.