There's a great article by Stephanie Pain in New Scientist about the freezing European winter of 1708/09.
Known as the Great Frost at the time, rivers and seas froze, livestock died in the fields, crops failed and many starved. Famine and food riots followed.
Results from tree ring analysis prove that it was the coldest winter in 500 years and temperatures throughout Europe were on average seven degrees colder than average twentieth century temperatures.
It's a fascinating read!