They took part in the Battle of Dallas during the last several days of May losing five men killed and fifteen wounded. Advancing further southward, they were lightly engaged in the Battle of New Hope Church and then took a position in front of Kennesaw Mountain in mid-June. On 27 June the advanced and participated in the Battle of Kennesaw Mountain. Their attack, like most of the other Union attacks, was bloodily repulsed by Confederates who were in heavily fortified earthworks. The continued to skirmish around Kennesaw Mountain and Marietta, Georgia, for nearly a month before advancing on Atlanta. On 22 July it seemed as though the Confederates had abandoned their trenches in front of the city, so the 111th was part of the force sent out to determine the enemy's location. After advancing near the enemy works they threw up breastworks and hoped to be the first regiment to advance into Atlanta. At about noon musketry was heard to their left and soon a division of Confederates came crashing down on the 111th. The regiment tried to hold back the enemy, but their vastly superior numbers soon forced the men to retreat. Being nearly surrounded they had to cut their way back to the rear. Their entire division had been crushed and those who were not killed or captured sped to the rear. General Logan personally rallied the men and organized a counter-attack to take back the trenches that had been lost. By nightfall, the 111th had reoccupied their entrenchments and the Union army had succeeded in turning back Hood's assault. During the Battle of Atlanta the regiment lost twenty killed, forty-five wounded, and eighty missing/captured. It was the bloodiest day in the regiment's service.