the fourth Carlist, or Bourbon traditionalist, pretender to the Spanish throne (as Charles VII) whose military incompetence and lack of leadership led to the final decline of the Carlist cause.

Don Carlos was the great-grandson of Charles IV (reigned 1788–1808) and the eldest son of the third Carlist pretender, Don Juan de Borbón, who abdicated on his behalf during the Revolution of 1868, which deposed Isabella II. Taking advantage of the resulting political instability, Don Carlos rallied his forces and provoked a bloody civil war, the Second Carlist War (1872–76). Although the Carlists scored some notable successes, their cause was doomed by the accession of Isabella's son Alfonso XII to the throne in 1874.

Don Carlos fled and became a wandering exile. He failed to exercise leadership to implement his claim either at the death of Alfonso (1885) or at the time of national discontent following defeat in the Spanish-American War (1898). At his death the Carlist party, divided by the development of regionalist parties and the advent of liberal Roman Catholicism, was disillusioned and fragmented.