Endurance by Right was sired by Inspector B, the 1886 Belmont Stakes winner, out of the imported British mare Early Morn.

Early Morn was bought by Milton Young, owner of McGrathiana Stud, in December 1898 while in foal with Endurance by Right.

[2] The filly was foaled in spring 1899 at McGrathiana and was put up for sale at the 1900 Woodward and Shanklin auction in Lexington.

Her early efforts showed potential and John Schorr offered to buy her outright from Barnes for $1,200.

[6] Endurance won the 1901 Champagne Stakes for Whitney,[7] but did not race as a three-year-old in 1902 due to perceived illness.