The companies were recruited principally:
A at Hudson, Greenport, New Lebanon, Livingston, Claverack and Ghent
C at Hudson, Taghkanick, Copake, Stockport, Livingston, Gallatin, Claverack, Stuyvesant and Germantown;
D at Brooklyn, Hudson, Fishkill and Ghent;
E at Ghent, Claverack, Hudson, Copake, Livingston, Hillsdale, Fishkill, Greenport,
Stuyvesant and Taghkanick;
G at Hudson, Kinderhook, Claverack, Stockport, Ghent, Chatham, Taghkanick, New Lebanon, Fishkill and Poughkeepsie;
I at Hudson, Poughkeepsie, Gallatin, Livingston, Pleasant Valley and Taghkanick

B, H and K at Brooklyn and F at Brooklyn and Brookhaven by Lieutenant Colonel Molineux

Irish Bend

The regiment was ordered to advance at the double quick across an open field against a Confederate line sheltered by a fence and woods. The 159th came within 50 yards of the enemy before halting to commence fire. Colonel Molineux had just given the order to continue the advance when a rifle ball entered his mouth and passed out his left cheek, carrying away half his upper jaw, and at the same moment a Confederate attack struck the regiment’s flank. The 159th was almost out of ammunition, and was ordered to fall back to the edge of the field. But reinforcements moved up against the Confederates, who retreated.

The regiment lost Lieutenant Colonel Draper, Adjutant Robert Lathrop, 1st Lieutenant John Manley Jr., 1st Lieutenant William R. Plunkett, 2nd Lieutanant Byron F. Lockwood, Second Lieutenant Charles P. Price and 30 enlisted men killed and mortally wounded; Colonel Molineux, 2nd Lieutenant William F. Tiemann, Captain Wells O. Pettit, and 62 men wounded; and 16 men missing. It was the greatest loss of any regiment in the fight. Amazingly, Colonel Molineux survived to return to command the regiment.

Major Burt, who had been detached to Genral Grover’s staff, was promoted to lieutenant colonel and took command of the regiment. Captin Edward Gaul was promoted to major.

Governor Welles of Louisiana gave Colonel Molineux a bear cub, who the colonel presented to the regiment as a mascot.

Assault on Port Hudson

After a long approach march, an unsuccessful attack was made that got within 30 yards of the Confederate defences. Color Corporal Jonathan Race was killed and Color Sergeant William Spanburg wounded in three places and the color staff shot into two pieces. 14 men were killed, and Captain Charles Lewis and 39 men wounded, four of whom later died. The regiment huddled on the field until after 11 p.m., when it withdrew. It temporarily consolidated into five companies afterward due to a lack of company officers.

Second Assault on Port Hudson

the second assault was also unsuccessful, costing 14 men wounded and 2 missing.

Surrender of Port Hudson

One thousand volunteers were called for to create a storming column and the regiment provided 18 men, but the Confederates surrendered their position before the assault could be made.

Skirmish at Halltown

Captain Wells Petit was badly wounded and 9 enlisted men wounded, 2 mortally.

On Skirmish line at Berryville.

Henry Karcher was killed to artillery fire.

Battle of Winchester

The regiment lost Lieutenant Herman Smith and 11 men killed or mortally wounded, Captain Joseph McNutt, Lieutenants Edward Duffy, Henry Howard and 40 enlisted men wounded, and Captain William Tiemann and 19 men captured, of whom 8 later died in captivity.

Battle of Cedar Creek

The regiment lost Major Robert M. Hart, Captain Duncan Richmond, 1 other officer and 4 enlisted men killed or mortally wounded, First Lieutenant Barzillai Ransom and 10 enlisted men wounded, and 6 men missing. Major Hart had been serving on General Grover’s staff and fell into Confederate hands after being wounded, dying from loss of blood after being recaptured in the afternoon. Three Confederate officers and 31 men were captured in a charge during the second phase of the battle.