Short answers, pulled from the story.
Hans Christian Ørsted made the discovery in 1820 when he noticed a compass needle deflecting as an electric current passed nearby. This observation proved that electricity and magnetism were two sides of the same coin and birthed the field of electromagnetism.
The War of Currents was a brutal commercial and technical battle in the late 19th century pitting Thomas Edison's direct current system against George Westinghouse's alternating current. Edison switched on the world's first large-scale electric power network on Manhattan Island in 1882, but alternating current ultimately won due to the technical superiority of the transformer and systems developed by Nikola Tesla and Mikhail Dolivo-Dobrovolsky.
John Bardeen and Walter Houser Brattain invented the transistor in 1947 at Bell Telephone Laboratories. This point-contact transistor was a tiny semiconductor device that replaced bulky vacuum tubes and enabled the creation of integrated circuits and the microprocessor.
Electrical engineering became a decisive factor in the Second World War through the development of radar and the first electronic computers. The British military operated the first radar station at Bawdsey in August 1936, and Tommy Flowers designed the Colossus computer in 1943 to break German codes.
The global electric telegraph network was established in the latter half of the 19th century with practical systems developed by Francis Ronalds in 1816. Units such as the volt, ampere, coulomb, ohm, farad, and henry were agreed upon at an international conference in Chicago in 1893.