12 September 1895,
The Spanish authorities closed the Euzkeldun Batzokija and confiscated the ikurrina. By order of the government authority of St. Leoncio, he stopped the board of directors of the first batzoki and prosecuted the 100 partners of the association. The PNV was founded two weeks after the arrest of Sabino Arana and soon after the Spanish authorities closed the magazine Bizkaitarra. According to rumours, this first ikurrina was deposited in the Bilbao Court until 1932 and today it is considered missing. Euzkeldun Batzokija was the precursor of the current batzokis.
Source:
Frequently asked questions about Basque symbols (Sabino Arana Foundation).