Which battle was characterized as one of the bloodiest single days in the Atlanta campaign?

The Battle of Kennesaw Mountain is recognized as one of the bloodiest battles during the Atlanta campaign, which took place in 1864. This battle saw fierce fighting and significant casualties on both sides as Union General William Tecumseh Sherman sought to seize control of the strategic city of Atlanta. The battle’s intensity stemmed from the Confederate forces' strong defensive positions on the high ground, making it a particularly challenging engagement for Union troops.

The outcomes of this battle were pivotal, as the Union's frontal assaults against entrenched Confederate defenses resulted in over 4,000 casualties in a single day. This high number of casualties underscores the battle's notoriety within the broader Atlanta campaign context, which aimed to disrupt the Confederate supply lines and logistics.

In contrast, other battles listed, such as the Battle of Gettysburg, while extremely significant and bloody, occurred during earlier phases of the Civil War and were not part of the Atlanta campaign. The Battle of Chickamauga also had high casualties but was a separate engagement. The battles of Marietta do not carry the same historical weight in terms of bloodshed or significance in this particular context. Thus, Kennesaw Mountain stands out as a defining moment in the Atlanta campaign.