12 March 1986,
No to NATO in Hego Euskal Herria. 40.9% voted against, 21.5% against and 34.9% abstention. Result in votes: no, 828,721; yes, 434,553; abstention: 706,311; white: 43.450; Null: 12.382. He also won the negative in Catalonia and the Canary Islands. Winning the referendum was the highlight of a terrible campaign.
Source:
Sabino Ormazabal, Grupo Bidea Xede. 500 non-violent actions. (MR Arangiz Foundation)