The Pemmican War was fought over the lucrative pemmican trade. Dried bison meat was ground with fat and berries to make "pemmican". British polar expeditions fed a type of pemmican to their dogs as "sledging rations". Pemmican was made with moose or caribou. Jerky and pemmican are high-energy and lightweight. It was boiled, dried, and made into pemmican. The extra meat was preserved as pemmican. The meats used in contemporary pemmican may also include beef. This allowed for the tough meat to be dried and made into pemmican. The Red River pemmican was absolutely vital to the NWC. Alexander Mackenzie relied on pemmican on his 1793 expedition across Canada to the Pacific. Pemmican and maple sugar were also commonly added to the mixture. It was an outpost of Fort Ellice and was mainly a source of pemmican. The post also produced pemmican and York boats. In 1818 the Pemmican War trials commenced.