Here's the background I've written for my personal version of The Christmas War. All campaign participants are welcome to steal any piece of this for your own games, or use the whole thing if you like!
Avalonia was an early Earth colony, found in 2112 AD. Two separate colonies were establisehd on Avalonia: Cimmeria in the south and Laurentia in the north. Cimmeria became the most populous of the two colony-states: about seven million colonists within the first few generations. Laurentia was less than half of that size, but its settlers brought significant intellectual and technological advantages compared to the Cimmerians. Laurentia carefully established their early settlements where they could best utilize their own resources. Cimmeria simply tried to shelter its people as best it could, relying on Laurentia for assistance.
Tensions between the Laurentia and Cimmeria were inevitable. Things took a turn for the worse when Cimmerian territory experienced a significant temperature increase. Their soil had already been badly damaged by poor agricultural conservation practices, but the climate change significantly degraded their ability to grow crops and raise livestock. Cimmeriaâ€™s food production now consisted mostly of rice products and a poor-tasting fish that seemed to be a close relative of Earthâ€™s sardine. It had effectively become a poverty-stricken nation, and its people were suffering greatly.
Laurentia, comparatively, had become a paradise. They had adapted numerous grasses, vegetables, and grains to Avaloniaâ€™s red soil, and the climate was favorable for all kinds of livestock. They also discovered enough petroleums, natural gasses, metals, and minerals to last for many future generations. Laurentiaâ€™s communities developed rapidly, and their level of industrial and agricultural automation granted its people more than enough time for recreation and higher education.
Laurentia eventually ceased exports. They felt they had provided Cimmeria every opportunity to adapt into a self-sufficient society, which Cimmeria squandered in favor of more â€œhandouts.â€ Laurentia relocated the majority of their military installations to the border with Cimmeria. Cimmeria, using the only resources they had available (people and industry), had significantly increased the size of their military over the past generation.
On the eve of their hundredth Christmas, Laurentiaâ€™s administration invited Cimmeriaâ€™s leaders to a summit. They were prepared to offer them one last chance to send their agricultural leaders into Laurentia for training. While Laurentiaâ€™s administration was giving the Cimmerian delgation a tour of their government facilities, the Cimmerians noticed how empty the offices and hallways seemed. A Laurentian aide made the mistake of saying that not only had most government employees taken vacation to see their families, but most of their military had done the same. This was what the Cimmerians were waiting to hear. One of the Cimmerians reached into his pocket and clicked his pen three times. The microtransmitter inside the pen sent the signal to their military forces - launch the attack!