- Mar 5 Parma, Tuscany, Modena and Romagna vote in referendums to join the Kingdom of Sardinia
- Mar 7 22nd Grand National: Tommy Pickernell wins aboard Irish horse Anatis at 5/1
- Mar 9 1st Japanese ambassador arrives in San Francisco en route to Washington
Treaty of Interest
Mar 17 Six years after the forcible ending of Japan's isolationist policy by US Navy Commodore Matthew C. Perry, the Japanese Embassy arrives in San Francisco to sign a Treaty of Friendship

Matthew C. Perry
- Mar 21 US extradition treaty with Sweden
Event of Interest
Mar 21 English novelist George Eliot finishes her novel "The Mill on the Floss" in Wandsworth, London

George Eliot
Theater Premiere
Mar 29 Dion Boucicault's play "Colleen Bawn" premieres in NYC

Dion Boucicault