Hernan Cortés was a Spanish conquistador sent on an expedition to colonise Mexico in 1517. With 11 ships and 600 men, he landed on the Mexican coast and travelled to Tenochtitlan to meet Moctezuma, ruler of the rich and prosperous Aztecs.

Cortés hadn’t exactly come in peace – but Moctezuma welcomed him anyway, possibly because he thought it was best to get to know the Spanish in order to defeat them later.
Moctezuma gave Cortés ‘chocolatl’, his favourite drink, served in a golden goblet. Apparently Moctezuma used to drink it before going to his harem, and ever since then chocolate has had an (unfounded) reputation of being an aphrodisiac.
Poor old Moctezuma was put in prison by Cortés. He became ruler again briefly under Spain, but was then killed by disgruntled Aztecs in 1520, and by July of that year the Aztecs had forced the Spanish out of Tenochtitlan. The Spanish retaliated, holding the city in siege for 75 days until it fell, marking the end of Aztec civilisation.
Cortés was made Captain General and Governor of Mexico. And he never forgot about chocolate – when he returned to Spain in 1528 he loaded his galleons with cocoa beans and equipment for making the drink. Soon 'chocolate' was all the rage amongst the Spanish elite. They kept quiet about it though! It took nearly a century for news of cocoa and chocolate to spread across Europe.
Read about how chocolate spread across Europe