“At the outbreak of the war, the regiment with which he was serving was recalled from California, and on the organization of the army under McClellan, was attached to the Regular Cavalry Division, which took part in the principal battles in the campaign of the Peninsula, during which O’Neill was in command of Gen. Stoneman’s body guard. After the withdrawal of the army from the Peninsula, he was dispatched to Indiana, where he was retained for some time as instructor of cavalry, drilling the officers of the force then being raised for the defence of that portion of the Union against the incursions of the Confederate guerillas. He subsequently entered the 5th Indiana Cavalry as Second Lieutenant, and served with that regiment, during 1863, in the operations against the Southern leaders in Kentucky, Tennessee, Indiana and Ohio. In these expeditions, which, whether in the nature of scouts, reconnoisances or advances, generally took the shape of sharp running fights, Lieut. O’Neill’s skill and daring not only attracted the attention of his commanding officers, but further enlisted the enthusiasm of the men, insomuch that, when one of those sorties was ordered, the first question asked was always—‘Is O’Neill to lead it?’—and if the answer was in the affirmative, no matter how jaded the men might be, volunteers in any number were ready at once.
“There is no greater instance of personal bravery, or gallantry equal to any emergency, than that related by Archbishop Purcell, of Cincinnati, in his account of O’Neill’s encounter with Morgan, the famous guerilla; and as many of our readers have not read the partial account given in Mr. Savage’s ‘Fenian Heroes and Martyrs,’ it may prove of interest to them, as his encounter with Morgan is more generally spoken of than understood. Archbishop Purcell says:—
‘There is a remarkably brave officer suffering from diarrhoea, contracted in a three month’s chase after Morgan, now in St. John’s Hospital, in this city—Lieut. O’Neill, of the 5th Indiana Cavalry. His mother resides in Elizabeth, New Jersey. Her adventurous boy enlisted in the regular army at the time of the Mormon excitement in Utah; was afterwards sent to California; was made Sergeant for distinguished services on the Potomac; employed on a recruiting tour in Indiana, and promoted to a Lieutenancy in the famous 5th Indiana cavalry.
‘Respecting his encounter with Hamilton’s rebel force, in May, the Indianapolis papers spoke of the exploit of Lieut. O’Neill, and a detachment of his company, as one of the most daring and brilliant achievements of the war. The Lieutenant has kindly furnished us with the following interesting account of the part he took in the defeat of Morgan. The authorities here have recommended him for promotion to the rank of Major.
‘INCIDENTS OF THE FIGHT WITH MORGAN, AT BUFFINGTON’S ISLAND, ON THE 20TH OF JULY.
‘On the night of the 19th, about 10 o’clock, Gen. Judah, with his cavalry and artillery command, left Pomeroy for Buffington. The General sent First Lieutenant John O’Neill, of the 5th Indiana cavalry, with fifty men, ahead, with instructions to try and open communications with the militia, said to be in close proximity to the island. The Lieutenant was delayed by losing the road during the night, and did not arrive till about an hour and a half after daylight. He then learned that the militia had been skirmishing with the enemy during the night, and that Gen. Judah’s advance had been ambushed, the morning being foggy; and the General’s Assistant Adjutant General, Capt. Rice, with some twenty-five or thirty men and a piece of artillery, and Chief of Artillery, Capt. Henshaw, had been captured and sent to Gen. Morgan’s headquarters on the river road, some thirty miles ahead of him, on the enemy’s left flank. The Lieutenant at once resolved to recapture what had been taken; and, with his Spartan band, kept steadily on. Several parties tried to stop him; but a volley from the “Sharp’s” carbines of his boys invariably drove them back. At length he came on Morgan, with two regiments and a body guard of one hundred men. The Lieutenant halted his men suddenly, at an angle of the road, within one hundred and fifty paces. He gave the command “ready,” and intended to have given them a volley; but seeing some of his own men in front, he did not fire, but commanded “forward,” and dashed in amongst them. If he had fired, every shot must have told, he was so close. Morgan, with his two regiments and body guard, ran without firing a shot. All our prisoners were released, and about thirty of the enemy taken. Some were killed and wounded. The Lieutenant pursued Morgan about two miles clear off the field, and captured three pieces of artillery, which he carried off with him. This was the last of Morgan on the field. The Lieutenant cannot tell how many he killed or wounded, as his fight was a running one, extending over four miles; but the surgeon in charge of burying the dead and looking after the wounded, reported that most of both were along the river where O’Neill had been.’
“The above, from Archbishop Purcell, is an unquestionable testimony of the daring and audacity of the subject of this sketch in the field. The National Journal, in giving an account of the same battle, says:
‘Lieutenant O’Neill, of the 5th Indiana Cavalry, now appeared by another road, with but fifty men, and charged two different regiments so desperately that they broke and left our captured guns, officers and men in our possession.’
“The Louisville Journal, after relating an instance of O’Neill’s personal bravery, says:
‘Lieutenant O’Neill is the same who, about two weeks ago, while out with Col. Graham, on the Tennessee side of Cumberland, with twenty men as an advanced guard, came up with Hamilton, having two hundred men drawn up in line—charged and ran him thirteen miles, and with his own hand, while ahead of his men, killed five—two of them with the sabre.’