In 1513 he returned to Spain, still in the service of Medina Sidonia. At some point he married María Marmolejo, member of a prominent "converso" family in Seville. When the Revolt of the Comuneros broke out in 1520 against the new Spanish king, Charles V, Cabeza de Vaca fought alongside the duke on behalf of the crown. When the "comuneros" tried unsuccessfully to seize control in Seville in September, the duke put him in charge of defending one of the city gates; in December he fought to liberate the city of Tordesillas; and on 23 April 1521 he participated in the defeat of the "comuneros" at the battle of Villalar. Later in 1521 when the French king, Francis I, invaded Navarre, Cabeza de Vaca fought against them in the battle of Puente de la Reina.