In 1802, When Napoleon gained control of Spain, he drew up a new constitution. He let the Fueros remain in place in the Basque country, but said they would be subject to review at a later date. He banned the Basque language in France's uniform school code. This act was not repealed until 1981.
In 1813, the Spanish-Portuguese-British alliance was able to finally drive Napoleon out of Spain. In the time he was there, he was able to leave a sizeable footprint, greatly affecting the Basques and their future struggles. Napoleon changed Spain forever by developing a new type of nationhood, with a constitution, which gave rise to the idea of Spain as a nation-state, not just a geographic location made up of inherited kingdoms.
After the defeat of Napoleon, the Liberals, a group of radicals in Cadiz who had escaped the war, believed that the way to prevent future takeovers was by a strong central government, including the Basque region. In 1812, the Liberals drew up a constitution which dismantled the Fueros. For the first time in their history, the Basques were without their ancient laws.