The Purnell Legion Maryland Infantry lost 1 officer and 42 enlisted men killed or mortally wounded and 1 officer and 73 enlisted men to disease during the Civil War. It is honored by a monument at Antietam.

1861
October 31 to December 31 Organized as a legion of nine companies of infantry, two companies of cavalry, and two batteries of light artillery by Colonel William Purnell, Postmaster of Baltimore, at Pikesville Arsenal, under special authority of the Secretary of War. Attached to Dix’s Division, Baltimore, Maryland.
November 14-22 Expedition through Accomac and Northampton Counties, Va.
1862
February Colonel Purnell resigned and the Legion was broken up into a regiment of infantry, two independent companies of cavalry and Battery A and Battery B, Maryland Light Artillery.
March Duty at Baltimore and with Lockwood on Eastern Shore, Va. assigned to Lockwood’s Brigade, Middle Department
March 17 William J. Leonard was appointed colonel.
April 8 Captain Benjamin L. Simpson of Company A was promoted to major.
May 25 Ordered to Harper’s Ferry and attached to 2nd Brigade, Sigel’s Division, Department of the Shenandoah
May 28-30 Defense of Harper’s Ferry
June Operations in Shenandoah Valley, Va., assigned to 2nd Brigade, 2nd Division, 2nd Army Corps, Pope’s Army of Virginia
July 23 Major Simpson was promoted to lieutenant colonel.
August 9
Battle of Cedar Mountain
August 16-
September 2
Pope’s Campaign in Northern Virginia assigned to 3rd Brigade, 2nd Division, 2nd Corps, Army of Virginia
August 21-23 Fords of the Rappahannock
August 22 Catlett’s Station

Colonel Leonard was captured.

August 27-29 Plains of Manassas (Reserve)
August 30 Second Battle of Bull Run (Reserve)
September 6-22 Maryland Campaign. Assigned to 3rd Brigade, 2nd Division, 12th Army Corps, Army of the Potomac.
September 14 Battle of South Mountain (Reserve)
September 16-17
Battle of Antietam

From the monument to the west of the Dunker Church:

Occupied a line running north from this marker. Loss, 3 killed, 23 wounded.

From the first of three War Department markers for Goodrich’s Brigade on the Antietam battlefield:

Goodrich’s Brigade was detached from its Division, when east of Joseph Poffenberger’s, and ordered to the assistance of Doubleday’s Division. It crossed the Hagerstwon Pike near Miller’s, formed in the north part of the West Woods and on the open ground east of them and, supported by Patrick’s Brigade, advanced in the direction of the Dunkard Church. When nearing this point it was stubbornly resisted by the enemy posted in the woods immediately southwest of this, and Colonel Goodrich was mortally wounded. The loss in the Brigade was heavy and it was obliged to retire.

From the second of three War Department markers for Goodrich’s Brigade on the Antietam battlefield:

When nearing the East Woods, early on the 17th, Goodrich’s Brigade was detached from its Division and ordered to the assistance of Doubleday’s Division engaged north of this. The Purnell Legion was detached near D. R. Miller’s and did not participate with its Brigade in the action near this point, but was engaged with its Division west of the Dunkard Church. After the repulse of the Brigade near this point, the 78th New York was detached.

From the last of three War Department markers for Goodrich’s Brigade on the Antietam battlefield:

Goodrich’s Brigade was detached from its Division, and supported Gibbon’s and Patrick’s Brigades of the First Army Corps in the fields and woods west of this point.

From Lieutenant Colonel Simpson’s Official Report on the Purnell Legion at AntietamL

We entered the field about 7 o’clock, and were immediately detached from our brigade, by order of General Williams, and sent to the support of the One hundred and twenty-fourth Pennsylvania Regiment, which position we held until ordered away. It entered the woods on the right of a white school-house [Dunker Church], where it formed in line and went into action, where it remained until the enemy appeared in overwhelming numbers and compelled it to retire. It fell back to the woods on our right, where our artillery were stationed, when we again formed in line, and went into camp with the brigade.

September 22 Moved to Bolivar Heights
September 24 Colonel Leonard was paroled and released from Libby Prison in Richmond.
October Assigned to 2nd Brigade, 2nd Division, 12th Army Corps
November 9 Reconnaissance to Rippen, Va.
November 26 Colonel Leonard resigned due to “family affliction” and private business.
December Detached and assigned to duty at Frederick, Md., and in the Middle Department
December 5 Lieutenant Colonel Simpson resigned.
1863
January 12 Captain Samuel A. Graham of Company D was promoted to colonel.
February Assigned to 3rd Separate Brigade, 8th Army Corps
June Assigned to 1st Separate Brigade, 8th Army Corps
1864
May 26 Joined Army of the Potomac in the field, assigned to 3rd Brigade, 2nd Division, 5th Army Corps
May 30-June 15 Rapidan Campaign
May 30 Shady Grove
June 1-12
Cold Harbor
June 1-3 Bethesda Church
June 16-18 First Assault on  Petersburg; Siege of Petersburg begins. Attached to 2nd Brigade, 2nd Division, 5th Army Corps
June 21-23 Jerusalem Plank Road
July 30
Mine Explosion, Petersburg

Colonel Graham was shot in the hand.

August 18-21 Weldon Railroad
September 29-October 2 Poplar Springs Church
October 2-5 Yellow House
October 7-8. Peeble’s Farm
October 24 Mustered out under the command of Colonel Graham. Veterans and Recruits were transferred to the 1st Maryland Infantry.