la historia del olvidado Estado neoincaico de Vilcabamba

What does “la gota que derramó el vaso” mean in Spanish?

La gota que derramó el vaso literally means “the drop that overflowed the glass,” Spanish’s version of “the last straw.” A history clip about the Neo-Inca state of Vilcabamba uses it at the exact turning point: after years of stalled negotiations with Spain, “la gota que derramó el vaso fue que dos enviados españoles a Vilcabamba fueron asesinados,” giving the Spanish crown its excuse to invade and end the last independent Inca state in 1572.

Historians now think Túpac Amaru I was likely innocent of that killing, but Viceroy Francisco de Toledo used it as the legal justification he needed: Inca ambassadors were untouchable under “the law observed by all nations,” so their deaths gave Spain grounds for a war it had wanted anyway. The Inca was captured, tried, and beheaded in Cuzco in September 1572, closing the book on a state that had resisted Spanish rule for nearly four decades.