January 1st - Benito Juárez captures Mexico City.
January 2nd - Friedrich Wilhelm IV of Prussia dies and is succeeded by Wilhelm I.
January 3 – Delaware votes not to secede from the Union.
January 9 – Mississippi becomes the second state to secede from the Union.
January 10 – Florida secedes from the Union.
January 11 – Alabama secedes from the Union.
January 12 – Major Robert Anderson, commander of Fort Sumter sends dispatches to Washington.
January 16 – Karl Marx, in London, writes to Ferdinand Lassalle in Berlin: "Darwin's book is very important and serves me as a basis in natural science for the class struggle in history.
January 19 – Georgia secedes from the Union.
January 21 – Jefferson Davis resigns from the United States Senate.
January 26 – Louisiana secedes from the Union.
January 29 – Kansas is admitted as the 34th U.S. state.
February 1 – Texas secedes from the Union.
February 4 – In Montgomery, Alabama, the Provisional Confederate States Congress is formed by representatives from the first six break-away states.
February 8 – The Confederate States of America are formed, comprising the first six break-away States.
February 9 – Jefferson Davis is elected the Provisional President of the Confederate States of America by the Weed Convention at Montgomery, Alabama.
February 11 - The U.S. House unanimously passes a resolution guaranteeing non-interference with slavery in any state.
February 13 – The Siege of Gaeta, stronghold of the Neapolitan King Francis II, is ended by Piedmontese forces. Francis goes into exile.
February 18 – In Montgomery, Alabama, Jefferson Davis is inaugurated as the provisional president of the Confederate States of America.