The Battle of Trafalgar eliminates the French and Spanish naval fleets and allows for British dominance of the seas, a major factor for the success of the British Empire later in the century.
Most of the Latin American colonies free themselves from the Spanish and Portuguese Empires after the Latin American wars of independence.
First publicly funded telegraph line in the world—between Baltimore and Washington—sends demonstration message on May 24, ushering in the age of the telegraph. This message read "What hath God wrought?" (Bible, Numbers 23:23)
Earliest recorded air raid, as Austria employs 200 balloons to deliver ordnance against Venice.
Crimean War between France, the United Kingdom, the Ottoman Empire and Russia