1861:

May-Occupation of the Relay House
May 7-Routes between the cities of Philadelphia, Harrisburg, and Washington, through Baltimore are reestablished.

May 13-Union forces garrison Baltimore
May 31-June 1-Attack on the batteries at Aquia Creek, Virginia

June 10-July 7-Expedition to Rockville
June 11-Occupation of Cumberland
June 14-Skirmish near Seneca Mills
June 17-Skirmish at Conrad's Ferry
June 18-Skirmish at Edwards Ferry

July-Seizure of the schooner Georgiana
July 1-Police commissioners in Baltimore arrested
July 2-Crossing of the Potomac River
July 4-Skirmish at Harper's Ferry, West Virginia.
July 7-Skirmish at Great Falls
July 29 or August 3-Skirmish at Edwards Ferry, Maryland

August 18-Skirmish at Sandy Hook
August 27-Skirmish at Antietam Iron Works

September 4-Skirmish at Great Falls
September 12-17-Members of the Maryland Legislature arrested
September 15-Skirmish near Antietam Ford
September 17-Skirmish near Point of Rocks
September 18-Skirmish near Berlin, Maryland
September 24-Skirmish at Point of Rocks
September 29-Skirmish at Berlin

October 4-Skirmish near Edwards Ferry
October 21-Engagement at Ball's Bluff, Virginia
October 21-Skirmish near Edwards Ferry
October 22-Nov. 12-Affairs around Budd's Ferry/affairs around
October 22-Skirmish near Edwards Ferry

October 28-Skirmish near Budd's Ferry

November 3-11-Expedition into lower Maryland
November 9-Expedition to Matthias Point
November 14-Affair at the mouth of Martawoman Creek

December 8-Skirmish at Dam No. 5
October 11-Skirmish at Dam No. 4
October 15-Capture of the sloop Victory
October 17-21-Operation against Dam No. 5
October 19-Skirmish at Point of Rocks
October 25-Skirmish at Cherry Run, West Virginia
October 25-Skirmish at Fort Frederick

1862:

January 5-Bombardment of Hancock

May 24-26-Retreat to Williamsport

September 3-20-Maryland Campaign
September 3-4-Skirmish at Edwards Ferry
September 4-7-Crossing of the Potomac River
September 4-5-Skirmishes at Poolesville
September 4-Skirmish at Berlin
September 4-Skirmish at Monocacy Aqueduct
September 5-Skirmish at Point of Rocks
September 6-Evacuation of Frederick
September 7-Skirmish at Point of Rocks
September 8-Skirmish at Poolesville
September 9-Skirmish at Barnesville
September 9-Skirmish at Monocacy Church
September 10-11-Skirmishes at Sugar Loaf Mountain
September 10-Skirmish near Boonsborough
September 10-Skirmish near Frederick
September 12-13-Action on Maryland Heights
September 12-Skirmishes at Frederick
September 13-Skirmish at Catoctin Mountain
September 13-Skirmish at Jefferson
September 13 Skirmish at Middletown
September 13-Skirmish at South Mountain
September 14-Battle of South Mountain
September 14-Battle at Crampton's Pass
September 14-Skirmish near Petersville
September 15-Skirmish on Antietam Creek
September 15-Skirmish at Boonsborough
September 16-17-Battle of Antietam
September 18-19-Recrossing of the Potomac River
September 19-Skirmish at Sharpsburg
September 19-Skirmish at Shepherdstown Ford
September 19-Skirmish near Williamsport
September 20-Skirmish near Hagerstown
September 20-Skirmish near Williamsport

October 1-Reconnaissance from Sharpsburg
October 4-Reconnaissance from Conrad's Ferry
October 8-Reconnaissance from Conrad's Ferry
October 9-12-Stuart's Expedition
October 9-Skirmish at Four Locks
October 10-Capture of the signal station at Fairview Heights
October 10-Skirmish at McCoy's Ferry
October 10-Skirmish near Green Spring Furnace
October 12-Skirmish near the mouth of the Monocacy River
October 12-Skirmish at White's Ford/skirmish
October 16-17-Reconnaissance from Sharpsburg

November 24-25-Expedition from Sharpsburg
November 25-Raid on Poolesville

December 14-Raid on Poolesville

1863:

April 21-May 21-Jones' Raid
April 26-Affair at Altamont
April 26-Skirmish at Oakland

June 9-Aug. 1-Gettysburg Campaign
June 11-13-Expedition through Seneca Mills
June 11-Skirmish at Seneca Mills
June 15-Skirmish near Williamsport
June 17-Skirmish at Catoctin Creek
June 17-Skirmish at Point of Rocks
June 20-Skirmish at Middletown
June 21-Skirmish at Frederick
June 24-Skirmish at Sharpsburg
June 28-Skirmish between the Offutt's Cross-Roads and Seneca
June 28-Skirmish near Rockville
June 29-Affair at Lisbon
June 29-Affair at Poplar Springs
June 29-Skirmish at Muddy Branch
June 29-Skirmish at Westminster
June 30-Skirmish at Westminster
June 30-Evacuation of Maryland Heights

July 4-Skirmish near Emmitsburg
July 5-Skirmish at Cunningham's Cross-Roads, Pa
July 5-Skirmish at Smithburg
July 6-Hagerstown/action
July 6-Williamsport/action
July 7-Downsville/skirmish
July 7-Funkstown/skirmish
July 7-Maryland Heights/reoccupation
July 8-Boonsborough/action
July 8-Williamsport/skirmish near
July 9-Benevola/skirmish
July 10-13-Funkstown/skirmishes at and near
July 10-13-Hagerstown/skirmishes at and near
July 10-13-Jones' Cross-Roads/skirmishes
July 10-Clear Spring/skirmish near
July 10-Old Antietam Forge/skirmish
July 14-Failing Waters, W. Va./action
July 14-Williamsport/skirmish

August 27-Skirmish at Edwards Ferry

September 22-Skirmish at Rockville

1864:

April 12-14-Expedition from Point Lookout

May 1-Aug. 3-Mosby's Operations
May 5-Raid on the Baltimore and Ohio Railroad
May 11-14-Expedition from Point Lookout

June 11-21-Expedition from Point Lookout
June 23-Aug. 3-Early's Raid

July 5-Skirmish at Hagerstown
July 5-Affair at Keedysville
July 5-Affair at Noland's Ferry
July 5-Skirmish at Point of Rocks
July 5-Affair at Solomon's Gap
July 6-Affair at Antietam Creek
July 6-Capture of Hagerstown
July 7-Affair at Brownsville
July 7-Skirmish at Frederick
July 7-Affair at Hager's Mountain
July 7-Skirmish at Middletown
July 7-Affair at Solomon's Gap
July 8-Skirmish at Antietam Bridge
July 8-Skirmish Frederick
July 8-Skirmish at Sandy Hook
July 9-Battle of Monocacy River
July 9-Skirmish at Urbana
July 10-Confederates burn the Gunpowder Bridge
July 10-Skirmish near Monocacy River
July 10-Skirmish at Rockville
July 11-Skirmish at Frederick
July 11-Capture of trains at Magnolia
July 12-Skirmishes on the Northern defenses of Washington, D.C.
July 13-Affair at Rockville
July 14-Affair at Poolesville
July 25-Skirmish at Williamsport
July 29-Skirmish at Clear Spring
July 29-Skirmish at Hagerstown
July 30-Affair at Emmitsburg
July 30-Skirmish at Monocacy Junction
July 31-Skirmish at Hancock

August 1-Attack on Cumberland
August 1-Affair at Flintstone Creek
August 2-Skirmish at Hancock
August 2-Skirmish at Old Town
August 4-Skirmish at Antietam Ford
August 5-Skirmish at Hagerstown
August 5-Skirmish at Williamsport
August 5-Skirmish at Keedysville
August 22-Affair at Cove Point
August 26-Affair at Williamsport

14-Skirmish at Adamstown

1865:

February 21-Raid on Cumberland

April 5-Confederates capture the steamer Harriet De Ford at Fair Haven, Maryland