Diogo de Silves

Diogo de Silves, (15th century) is the presumed name of an obscure Portuguese explorer of the Atlantic who allegedly discovered the Azores islands in 1427.

He is only known from a reference on a chart drawn by the Catalan cartographer, Gabriel de Vallseca of Mallorca, dated 1439. The map, marred by an inkwell accident in 1869, has a note by the Azores archipelago, presumably written by Vallseca, stating:

Aquestes isles foram trobades p diego de ??? pelot del rey de portugal an lany MCCCCXX?II (Transl. "These islands were found by Diego de ??? pilot of the King of Portugal in the year 14??")

The surname and part of the date are smudged. The earliest reading we have of this portion of the map is by a Majorcan named Pasqual in 1789 (before the ink accident) who jotted the surname down as "Guullen". It has since been read by other investigators as Diego de Senill ('the Old' - a hopeful reference in the direction of Gonçalo Velho, who officially discovered the Azores in 1431). Others have proposed de Sevill or de Seville or de Sunis, Survis, Sinus, Simis, Sines, Sivils. The date has been variously interpreted as MCCCCXXVII (1427) or MCCCCXXXII (1432) or MCCCCXXXVII (1437).

In 1943, Portuguese historian Damião Peres proposed that only Diogo de Sunis or Diogo de Silves should be entertained as readings from the smudged surname, and opted for Silves simply because Portuguese surnames of that era are usually toponyms and that the town of Silves, in the Algarve, not far from the port of Lagos (where Henry was organizing his expeditions), was not unlikely. He also settled on interpreting the date as 1427. Peres's reading of name and date have since become common in Portuguese sources. The hypothesis has been sufficiently accepted that the Portuguese postal service saw fit to emit a stamp in honor of 'Diogo de Silves' in 1990.

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