February 14, 1876
Bell vs Gray
After years of independent research, two men each filed for a patent (or caveat) on February 14, 1876. One was Alexander Graham Bell; the other was Elisha Gray. Bell received patent #174,465 in March for what was later described as "the most valuable patent in history." Gray legally challenged the decision, but after a two year court battle, Bell went down in history as the inventor of the telephone.