On 03 Apr 1367 the forces of Peter "Cruel" I King Castile (age 32) commanded by Edward "Black Prince" (age 36) defeated the army of Henry "Fratricide" II King Castile (age 33) at the Battle of Nájera at Nájera. The English forces included John of Gaunt 1st Duke Lancaster (age 27), William Scrope, Peter Courtenay (age 21), John Devereux 1st Baron Devereux (age 30), John Savile of Shelley and Golcar (age 42), Bernard Brocas (age 37) and Thomas Banastre (age 33).

The forces of Henry "Fratricide" II King Castile (age 33) included Bertrand Geusclin (age 47). The battle achieved little since Bertrand Geusclin (age 47) escaped.

John Ferrers 4th Baron Ferrers of Chartley (age 36) was killed. His son Robert Ferrers 5th Baron Ferrers of Chartley (age 9) succeeded 5th Baron Ferrers of Chartley. Margaret Despencer Baroness Ferrers of Chartley by marriage Baroness Ferrers of Chartley.

Edward "Black Prince" (age 36) thereafter returned home, taking Peter's daughters Constance (age 13) and Isabella (age 12) as hostages to ensure Peter would pay the money owed to Edward. Constance (age 13) married John of Gaunt 1st Duke Lancaster (age 27), Isabella (age 12) married Edmund of Langley 1st Duke York (age 25).