March 4 – Abraham Lincoln is inaugurated.
March 6 – The new Confederate Congress authorizes the use of 100,000 volunteer soldiers for twelve months.
March 29 – President Lincoln, after seeking counsel, decides to reinforce Ft. Sumter and not abandon it to the South.
March 7/8 – Battle of Pea Ridge (Arkansas), also known as Elkhorn Tavern, is a Union victory and helps keep Missouri a Union State.
March 8 – Lincoln demotes McClellan to commander of just Army of the Potomac due to his cautiousness of prosecuting the Union war effort.
March 8/9 – Confederate iron-clad C.S.S. Virginia (formerly U.S.S. Merrimack) sinks two wooden Federal ships and runs others aground near Hampton Roads, Virginia. March 9th the C.S.S. Virginia duels with the U.S.S. Monitor to a draw. Dueling iron-clads will change naval history forever.
March 13 – U.S. article of war forbids Union army officers from returning fugitive slaves to their masters.
March 23 – Stonewall Jackson suffers a tactical defeat at the first battle of Kernstown in opening Shenandoah Valley Campaign.
March 3 – Congress passes the Conscription Act, calling for the enlistment in military service of all able-bodied males between 20 and 45 years of age for terms of three years.
March 6 – white mobs in Detroit riot in the black section of the city, killing several blacks.
March 10 – Faced with an estimated 125,000 deserters, Lincoln issues o general amnesty for all who will report back to duty.
March 2 – U.S. Grant named General-in-Chief of Union armies.
March 9 – Ulysses S. Grant receives formal promotion to Lt. General, the highest rank, only previously held by President George Washington.
March 18 – William T. Sherman assumes command of Union forces in the West.
March 25 – Union General Banks begins Red River campaign.
March 2 – battle of Waynesboro.
March 3 – Union Congress creates the Freedmen’s Bureau.
March 4 – Lincoln’s Second Inaugural Address
March 13 – Desperate now, Confederate Congress approves using black troops in combat.
March 19-21 – Sherman repulses Johnston’s attack at Bentonville, North Carolina.
March 24 – Sherman occupies Goldsboro, North Carolina, ending Caroilnas Campaign.
March 25 to April 2 – The Battle of Petersburg in Virginia.
March 28 – Lincoln, Sherman, Grant and Porter meet to confer on peace terms to end the long war.
March 29-31st – final Virginia Campaign begins with fighting around Dinwiddie Courthouse.
For a complete timeline of the American Civil War see the Civil War Gazette’s timeline here.