Why did Napoleon decide to attack Portugal?

Napoleon's decision to attack Portugal was primarily driven by his desire to enforce the terms of the Continental System, a blockade aimed at damaging the British economy by prohibiting trade between Britain and mainland Europe. Portugal was a neutral country that did not comply with this system, allowing British goods to flow into Europe through its ports. By invading Portugal, Napoleon aimed to tighten the blockade and eliminate a key loophole that allowed British trade to continue, thereby further isolating Britain economically. This military action was also part of a broader strategy against Great Britain, which was a significant adversary during the Napoleonic Wars.