Despite inflicting a heavy defeat that Sherman's Union forces at Kennesaw Mountain on June 27, within days the Confederate armies under General Johnston began withdrawing towards their next line of defences along the Chattahoochee River. On July 2, Johnston withdrew from Kennesaw Mountain south towards Smyrna and to the Nickajack Creek area four miles to the west. The Federals followed, rearranging the positions of the various armies and the corps that made up their structures.

'General Stoneman's cavalry connected promptly with my right, and fought with great spirit...assisting materially in driving the enemy.'

Located on the grounds of this 400 acre plantation was Mable House, later to be used as a Federal hospital. It is unclear if General Blair used the house for his headquarters as his reports from those days simply state, 'In the Field', but the next day was Independence Day, July 4, and the house would seem the ideal location to host the celebratory picnic he held for his officers and guests. Blair's adjutant general was Keogh's good friend, A. J. Alexander, who also happened to be the general's cousin. With Stoneman's cavalry now posted to the 17th Corps and Alexander's connections, it was no surprise that Major Keogh was among those invited to the festivities.
In the biography of A.J. Alexander - 'The life and services of Brevet Brigadier-General Andrew Jonathan Alexander' by James Harrison Wilson - the author recounts how the day's celebrations were suddenly interrupted and any feelings of complacency were dismissed as elements of Johnston's Confederate army began a counter attack:
"On the 4th of July, many officers of the various Corps, visited Blair's headquarters to enjoy their hospitality, and among others, Colonel Keogh, that gallant young Irishman, who had served with Alexander on Stoneman's staff ... On the day in question, while the enjoyment was at the highest and the woods were resounding with patriotic songs, a tremendous fire of musketry and artillery broke out on the extreme right, and called the merry revelers at once to the more serious business of the day. All jumped to their horses 'with hot haste', and hurried to their appropriate posts.This encounter, close to Ruff's Mill was with Georgia Militia, under Major General Gustavus Smith supported by General Ross' cavalry. Blair later recorded that his soldier's response pushed the enemy skirmishers back over a mile and towards their prepared defences - 'a heavy line of rifle-pits, on a commanding position from which they opened with artillery'. Again Stoneman's cavalry were at the heart of the action:
The enemy had sallied out from his lines, and was making a fierce attack. Matters looked serious for a while, but that was an army of veterans, every one of whom knew what to do in such an emergency. A sharp and bloody combat took place, and the Confederates were repulsed with heavy loss on both sides. As usual, Alexander was on the line, cool, steady and determined, duplicating the General, and directing and encouraging the men. The honors of the day were with the Union Army, but the battle had had a serious effect, and the celebration of the 'Glorious Fourth' was not renewed."
'During the operations of the day my right was covered by the cavalry, under Major-General Stoneman, who promptly and ably co-operated with me, his skirmishers connecting with mine and assisting materially in driving the enemy.'
'The skirmishers of Colonel Hall's brigade, in connection with General Stoneman's cavalry, made a determined and gallant attack on the enemy's line, approaching within 500 yards of the works, drawing the fire of the whole of the enemy's force from behind the works, and also that of two pieces of artillery.'
'The cavalry on my right have been very active, entirely covering that flank and keeping fully up with my advance.'

The casualties on the Union side during the day did not exceed 40 men but almost included Myles Keogh who, in the of act relaying an order, rode straight into a Confederate skirmish line. Recounting his near miss that day in a later letter to his sister, Ellen, he credited his horse, 'Tom', with saving his life:
'...my old charger that had carried me through so many dangers since the battle of Port Republic, when Keily was wounded. I wish you could have seen the poor fellow, how he could leap, and on the 4th of July he saved my life. Whilst riding on a bye road carrying an order I suddenly rode into a heavy outlying picket of the enemy. "Tom" saw them as they rose up to deliver their fire and jumped sideways over a rail fence into the wood skirting the road. He carried me safely out of range.
[From the collection of the Cayuga Museum of History and Art, Auburn]

By this time, Federal forces were within 15 miles of Atlanta, threatening the city from the west and north. An increasingly worried President Jefferson Davis and the Confederate government dispatched General Braxton Bragg to ascertain the situation with respect to Atlanta. His view was that, despite keeping his together as an effective fighting unit, Johnston had surrendered over one hundred miles of mountainous, and thus more easily defensible, territory in just two months. On July 17, 1864, President Davis removed Johnston from command and replaced him with the more aggressive Lieutenant General John Bell Hood. The change in leadership and tactics mattered for little as Atlanta fell into Sherman's hands at the beginning of September, 1864.
By that time, Major Keogh was experiencing life as a prisoner after participating in his bloodiest fight of the war - The Battle of Sunshine Church...