De Soto Discovering the Mississippi River, by Peter Frederick Rothermel (1843).
May 8: Hernando De Soto arrives at the Mississippi River, almost five months after entering present-day Mississippi.
Called Messippi, "Father of Waters," by the Indians, the massive river impedes De Soto's westward progress by a month as his men build barges in which to cross.
Though De Soto was a conquistador with visions of military conquest and lasting glory and fame for Spain (and for himself), ironically the most lasting and catastrophic effect of his expedition was the introduction of diseases for which the Native American population whom he encountered had no immunity.
Over the next generation some tribes were virtually wiped out by diseases introduced by the Europeans.