On 2 May 1808, an uprising broke out in Madrid against the occupation of the city by French troops, provoking a brutal repression by French Imperial forces and triggering the Peninsular War. Rebellions broke out across Spain and in June 1808 the Spanish lines were opened for the first time, allowing the now-allied British free access to the hinterland of Spain. The French responded to the Spanish rebellions by rushing armies to Spain to crush the Spanish uprisings around the country. This raised concerns in Gibraltar, where it was feared that the French could use the Lines to mount a fresh siege against the British territory. As they faced south, the Lines could not be used against an enemy approaching from the north.