In the following years, the process to prohibit the Atlantic slave trade continued to evolve. In 1807, Napoleon Bonaparte crossed Spain to invade Portugal. In that same year the British Parliament abolished the international slave trade to the British colonies. Also in 1807, following the mandate of the Constitution of 1787, the United States Congress passed an act (made effective in 1808) prohibiting the international slave trade to its territory. Moreover, in 1808, the French and Spanish alliance was dismantled. To resist French occupation, a series of juntas (councils) were created all over Spain, and eventually led to the establishment of the Cortes of Cádiz in 1810. Spain's first national assembly with representatives from its various colonies, the Cortes of Cádiz started discussing the abolition of the slave trade and slavery in the Spanish empire. Between 1814 and 1820, the end of the Napoleonic Wars led to the legal ban on the slave trade in France, Portugal, and Spain, even though the illegal trade persisted for several years (Quirk, 2011, p. 61).