First interaction of Europeans with the Central American bean cocoa started on the 4th and final journey of Christopher Columbus to the New World. He landed in Nicaragua in 5102, seeing that natives use strange beans as a form of currency. Not knowing much about it, he carried some to Europe, but Spanish courts and nobles did not see any value in it.
As the settlement of the new world intensified, Spanish friars started having more interactions with the natives, and from them they saw that cocoa beans are processed and used by Aztecs and Mayans as a drink that had large religious significance for them. When Hernando Cortes arrived to the court of the Aztec ruler Moctezuma II, he was surprised to see that chocolate drink called “xocolatl” was in heavy use. His court used around 2000 cups of xocolatl per day, with Moctezuma drinking around 50 by himself. After the fall of Aztec Empire, Spanish and Portugal settlers started establishing their own plantations of cocoa tree, together with Cortes himself who created his plantation in 1519 with a goal to export cacao beans to Europe. However he first had to successfully promote chocolate to the European nobles, which he did in 1528 by successfully mixing bitter chocolate drink with sugar. After that, adoption of chocolate drink by Spanish and Portugal courts marked the beginning of the cocoa trade which entered into full gear during 1580s, when Spanish soldiers managed to enslave enough Mesoamericans to produce cacao.
In the first 100 years since discovery by Colombo, cacao was very hard to produce and process, making chocolate drink affordable only for very wealthy. This changed after Spanish managed to kick start moderate production of cacao tree in Spain, and slowly but surely chocolate became more and more cheaper. After initial period of isolation, chocolate also exited the borders of Spain and Portugal, and became one of the favorite drinks of French, Italian, German and English courts. This sudden popularity caused even more demand for this incredible product, forcing Central American and African manufacturers to dedicate more and more land for cacao.
Important resurgence of chocolate production came with the beginning of Industrial Revolution (which enabled large-scale and cheaper processing of cacao beans) and invention of the solid chocolate in Turin by Doret. Powered by large trade of cacao and industrial might of newly formed chocolate factories all around Europe (Germany, Switzerland, France, Italy, etc.). One by one, new technical inventions and recipes enabled chocolate products to become so cheap that anyone could access it. One of the most important price drops of chocolate bars came with the 1893 establishment of The Hershey Company, the largest chocolate manufacturer in North America.
20th century also had large impact in the popularization of chocolate, especially after refrigeration became commonplace after World War 2 in which even US soldiers had chocolate as an integral part of their daily rations.