CEUTA, Spain — Tens of thousands of migrants who crossed into Spain’s tiny Ceuta territory returned voluntarily to Morocco on Friday, a day after the influx triggered chaos in the North African city and reignited the immigration debate in Europe and beyond. To reach Ceuta, on the northern African coast, migrants often swim from the Moroccan town of Fnideq, covering about 3 miles to reach Spanish territory. “Sánchez allows Spain to be invaded through Ceuta,” Spanish conservative politician Isabel Díaz Ayuso wrote on X. Pressure grows on second Spanish territory in AfricaMigrants from Morocco also attempted to cross into Melilla, the other Spanish territory at the tip of North Africa. There was widespread chaos in Bni Nsar, the Moroccan town bordering the Spanish territory, where migrants clashed with police, throwing rocks and setting police vehicles ablaze, according to local media and rights groups.