Many are familiar with the suffering of the Continental troops at Valley Forge; in actuality, the winters spent by the troops in Jockey Hollow were worse. On Christmas Day, 1776, Washington led his men across the Delaware River near the marker shown below. We are looking across from New Jersey to Pennsylvania.
This was taken on February 16, showing the river frozen over. Whether a river froze or not was a strategic consideration that affected a defensive posture or the possibility of attack. On February 18, 1776, Washington wrote the Continental Congress of the possibility of an attack on Boston: "The late freezing Weather having formed some pretty strong Ice from Dorchester point to Boston neck, and from Roxbury to the Common, thereby affording a more expanded and consequently a less dangerous Approach to the Town, I could not help thinking, notwithstanding the Militia were not all come In, and we had little or no Powder to begin our Operation by a regular Cannonade and Bombardment, that a bold and resolute assault upon the Troops in Boston with such Men as we had (for it could not take many Men to guard our own Lines, at a time when the Enemy were attacked in all Quarters) might be crowned with success . . . "
It is always worth remembering in this age of remote control drones, and high tech weaponry, the role of weather in war in general and the Revolution in particular. This was predominantly a land war, and even at that, mainly fought by foot soldiers, with limited cavalry involvement. When a river froze, a significant defensive feature was removed and an offensive advantage presented.