The Treaty of Tordesillas divides the ocean
Castile and Portugal agreed at Tordesillas to divide rights of navigation and possession outside Europe along a meridian drawn 370 leagues west of the Cape Verde Islands, everything west of the line falling to Castile and everything east to Portugal. The line moved a papal division of the previous year substantially westward at Portuguese insistence — a change that, six years later, put the Brazilian coast on the Portuguese side. The treaty is remarkable less for its arrogance than for its impossibility: no one could measure longitude at sea, the league itself had no single agreed value, and the parties did not specify from which of the Cape Verde Islands to count. The most consequential border of the sixteenth century could not be located by anyone who signed it.
Historical — it happened, and the record is settled.
Subjects
- Celestial navigation (latitude sailing) · technology · not located
- The Atlantic crossing (Carrera de Indias) · route · North Atlantic — Andalusia and the Canaries to the Caribbean, returning via the Gulf Stream and the Azores · not located
Evidence
Partly verified — Core facts are sourced; some optional detail is deliberately absent.
Treaty of Tordesillas
The text establishing the meridian 370 leagues west of the Cape Verde Islands as the division of navigation and possession between the two crowns. V55 verification basis: NOT consulted in this session. The 370-league figure is stated from the author's knowledge; the Memory of the World inscription is likewise recalled and its year is deliberately not stated. A curator should confirm both against the archives named.
Arquivo Nacional da Torre do Tombo, Lisbon, and Archivo General de Indias, Seville · 1494-06-07 · Partly verified
Treaty between Castile and Portugal signed at Tordesillas, 7 June 1494; original instruments held at the Torre do Tombo and the Archivo General de Indias, and inscribed on the UNESCO Memory of the World Register as a joint Portuguese–Spanish nomination
Recorded on Celestial navigation (latitude sailing)
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Related because they share a subject in the Atlas — never because the text looks similar.
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