Carlos likely rose to the kingship in the 1550s; William Marquart suggests 1556 based on events that happened that year. Carlos' succession evidently inspired challenges from other powerful chiefdoms. In 1556, the daughter of Oathchaqua, chief of the
Ais of
Cape Canaveral, set out for Calusa to cement an alliance between their peoples by marrying Carlos. During the journey, she was captured by the chief of the
Surruque or Serrope, who took her as his own wife. In doing so, Chief Surruque challenged Carlos' authority, disrupted the key alliance and trading route between the Calusa and Ais, and positioned himself as a significant power. A few years later, the
Tocobaga of
Tampa Bay asserted themselves by capturing twelve Calusa nobles, including the sister of Carlos' wife. Beset with problems, Carlos struggled to respond. Carlos reigned at the time of contact with the Spanish under
Pedro Menéndez de Avilés. Menéndez arrived in the Calusa region in 1566, five months after establishing the settlement of
St. Augustine in northeast Florida and ejecting the French
Huguenots from their settlement of
Fort Caroline. The Spanish landed at Carlos' capital, Calos, probably on
Mound Key. Menéndez' primary goal in the voyage was to secure the release of Spanish shipwreck survivors living among the Calusa, including his son Juan. Carlos jumped at the chance for an alliance with the powerful foreigners. He hoped such an alliance would help against his people's enemies, in particular the Tocabaga. He also may have hoped it would give him the upper hand in his rivalry with Felipe, whom the Spanish chronicler Gonzalo Solís de Merás wrote was even more feared by his people than Carlos himself. According to historian Stephen Edward Reilly, this power struggle was the primary reason Carlos pursued an alliance with the Spanish. Carlos attempted to solidify the alliance with the Spanish by offering to wed his sister Antonia to Menéndez, who very reluctantly accepted. He allowed the Spanish to establish a small outpost and a
Jesuit mission,
San Antón de Carlos, near the main town of Calos. He also sent several prominent Calusa, including Felipe, a certain Sebastian, and Sebastian's son Pedro (relatives of Carlos), on a trip to
Havana. However, relations with the Spanish soon soured. Carlos did reluctantly release his captive shipwreck survivors, but was angered when Menéndez refused to aid him against the Tocobaga. He was further dismayed when Menéndez put off consummating his marriage to Antonia (Solís de Merás is unclear as to whether they ever consummated the union). ==Death and aftermath==