The official first day of winter is the winter solstice, which falls on December 21 st each year. However, in meteorology, we consider the first day of winter to be the first day of December. The meteorological winter in the Northern Hemisphere runs from the first of December until the last day of February.

for more information … see below

Resource:

cute-calendar.com

earthnetworks.com

almanac.com

Determined to challenge the growing American military presence in their territory, Native Americans in northern Wyoming lure Lieutenant Colonel William Fetterman and his soldiers into a deadly ambush on December 21, 1866. With 81 fatalities, the Fetterman Massacre was the army’s worst defeat in the West until the Battle of Little Bighorn in 1876. Tensions in the region started rising in 1863, when John Bozeman blazed the Bozeman Trail, a new route for emigrants traveling to the Montana gold fields.

The Bozeman’s trail was of questionable legality since it passed directly through hunting grounds that the government had promised to the Sioux, Cheyenne and Arapahoe in the Fort Laramie Treaty of 1851.

Thus, when Colorado militiamen massacred more than two hundred peaceful Cheyenne during the Sand Creek Massacre of 1864, the Native Americans began to take revenge by attacking whites all across the Plains, including the emigrants traveling the Bozeman Trail.

The U.S. government responded by building a series of protective forts along the trail; the largest and most important of these was Fort Phil Kearney, erected in 1866 in north-central Wyoming.

Source: history.com for the complete article