According to Wikipedia and other sources, on July 27th:
1866 – The first permanent transatlantic telegraph cable is successfully completed, stretching from Valentia Island, Ireland, to Heart's Content, Newfoundland.
1905 – Leo Durocher, the American baseball player and manager, was born. (d. 1991)
1940 – Bugs Bunny made his debut in the Warner Bros. animated cartoon "A Wild Hare."
1984 - Pete Rose passes Ty Cobb as the all-time single leader when he collects his 3,053rd off Steve Carlton of the Phillies.
1987 – RMS Titanic Inc. begins the first expedited salvage of wreckage of the RMS Titanic.