Wyatt Berry Stapp Earp was born in the town of Monmouth, Illinois, on March 19, 1848.  He was the third son of Nicholas Earp and Victoria Ann Cooksey.  He was named after Nicholas' commanding officer during the Mexican War, Wyatt Berry Stapp.  Wyatt had two older brothers, James and Virgil, who were both born in Kentucky.

Sometime after Wyatt was born his family moved near the Dutch community of Pella, Iowa.  Nicholas had received a land grant of 160 acres in Iowa based on his service in the Mexican War.  Wyatt's two younger brothers, Morgan and Warren, were born in Iowa.  Much has been writted about the Earp brothers, but Wyatt also had three sisters.  Martha was born in Monmouth and she was a little more than two years older than Wyatt.  She died when she was ten years old.  The Earp family moved back and forth from Pella to Monmouth.  During one of these moves, Virginia was born in Monmouth.  Adelia, Wyatt's youngest sister, was born in Pella during 1861.

James and Virgil served with the Union Army during the Civil War.  James was seriously wounded and returned home in 1864.  Later that year, in May, the family headed west with a wagon train to California.   The Earp party encounter friendly Indians and hostile Indians.  Nicholas recalled one incident with hostle Indians:

We had no bin in camp long untell the Sentinels gave the alarm that the Indians was coming so I ordered the horses to be brought inside the corell by the gards that was garding them the women all turned out to help get the horses into the corell while e who was not on gard gethered our guns and rushed to meet the Indians when they got as clos as we entended them to come we commences poping away at them and soon succeeded in checking them and puting them to flite they ran off about a half mile and stoped and turned round as tho they war not satisfied.

I said bys they are not satisfied lets satisfy them so I ran to the waggons and jumped on a horse and said we'll make them leave here.  Dr. Rusau T. J. Ellis James Earp and a young man named Tucker that was with the Hamiltons and two other men that got in with us followed suit and off we charged after the Indians . . . .