Something very like this happened in 1816, known as "The year without a summer." However, in this case it was actually the "fallout", as it were, from the ash thrown into the atmosphere by the eruption of Mount Tambora in what was then known as the Dutch East Indies and is now called Indonesia. At the time, people did not understand exactly what was happening, as they had no way of figuring out that the eruption could have been responsible for all of this, even if they were aware of the eruption's occurring. They just staggered on as best they could considering all of the really bad things that were happening and would continue to happen for quite some time afterwards.