Is this grammatically correct: In October, 1347, after decades of trading the most luxurious goods, trading ships sailed into the port of Messina, Sicily, carrying a terrifying cargo--the disease now known as the bubonic plague, the infamous plague in which caused an estimated 25 million Europeans to die, about one-fourth to one-third of the population.

3 answers

Technically, it's correct. However, it's much too long and convoluted. You should rewrite it as two or more sentences.
In October, 1347, after decades of trading the most luxurious goods, trading ships sailed into the port of Messina, Sicily, carrying a terrifying cargo--the disease now known as the bubonic plague. This infamous plague caused an estimated 25 million Europeans to die, about one-fourth to one-third of the population.
That's much better.