Answer:
Lack of Farm Production
Great Britain, Spain, Mediterranean Pirates
The ensuing Mexican–American War was waged from 1846 to 1848 with the loss of many thousands of lives and the loss to Mexico of all of its northern provinces.
The astrolabe and the caravel <span />
St Petersburg was frozen and unusable for half the year
Also they didn't have fish to eat for half a year
So when that warm water port was acquired it was a game changer.
