From The Journal of the American-Irish Historical Society, Volume 27, 1928, page 271:

SWEENY AT SHILOH—April 6th, 1862
By James Edward Kelly

The Sabbath dawns on Shiloh,
From out the dark, gaunt pines,
Bursts Sidney Johnston's vanguard,
On Grant's raw, startled lines.
The dread ravine re-echoes,
With crash and batteries' roar,
Their rebel yell high pealing,
With Hardee at the fore.
Back huddling on the river,
Swirls Sherman's crushed command,
When, 'cross the course of conquest,
"Tom" Sweeny takes his stand.

Firm, cheerful, keen and valiant,
He curbs his chafing horse;
Amid his hard pressed soldiers,
He stands—an untold force.
His sword-arm sleeve hangs empty—
It tells them of his past;
This day, they feel, means victory,
Or it will be his last.
His lone left arm is wounded,
Down drops his bridle rein;
His horse is pierced by bullets,
He grimly mounts again.

The honor of the army,
Now rests with him today;
His men's true, steady volleys,
Repel the lines of gray.
Each mad assault grows stronger,
While his brave soldiers fall;
Re-echoing his order
The clear, crisp bugle's call:
"Bring up,—bring up—the colors!
'Tis answered 'mid a cheer—
His thin line rallies 'round him,
With colors in his rear.

He says: 'We're here to die men!
While, lit by sunset glow,
His flag pikes point to Heaven,
His bayonets to the foe.
He saves Grant's waning glory,
And Sherman's laurels, too,
While Buell's rescue column
Comes bristling into view.
Then, swaying in the saddle,
He's slowly led away,
While cheers ring out for Sweeny,—
The "savior of the day!"


[Note that no chorus is indicated as such.

The poem is also in Through American and Irish wars: the Life and Times of General Thomas W. Sweeny, 1820-1892 by Jack Morgan (Dublin: Irish Academic Press, 2006).

This summary of the book was apparently supplied by the publisher:

This biography traces the life of Thomas W. Sweeny, who, born in Cork, came to America at the age of twelve with his mother. His life was one of war and adventure and, also shows the way in which the Irish became prominently involved in events such as the Mexican War, the Indian wars, the settlement of California, the Civil War and ultimately in post-Civil War Fenian efforts toward the liberation of Ireland. Sweeny, who rose from a Lieutenant of Volunteers to the rank of General in the US Army, was the Fenian Secretary of War and the designer of the 1866 Fenian invasion attempt on Canada. The book captures the rugged, spirited times during which a large population of Irish settled into American geographical and cultural space.