Pope Leo II became the bishop of Rome.
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Balloonist John Wise started the world's first airmail service by balloon from Lafayette to Crawfordsville, Indiana.
Younes Abouyaaqoub drove a van into pedestrians on La Rambla in Barcelona, Spain, killing 14 people and injuring at least 130 others.
Solymon Merrick patented the wrench tool.
Asaph Hall discovered Mars' second moon, called Phobos.
A tropical cyclone hurricane hit Galveston in Texas.