I've gotten the update finished! Feel free to criticize and point out any inaccuracies, as I'm not sure if I have realistic communication or movement times. Also, I have a map ready, but I'll upload it later this morning.
Part Twelve: The Summer Campaigns
Summer of 1846:
Word of the outbreak of hostilities in Oregon spread quickly to the two governments, but it reached Washington first. The United States ordered troops to advance northward to stop the British from sending further supplies to Oregon via land. Echoing the War of 1812, most of the fighting was centered around the Great Lakes. However despite small gains by either side during the summer months, the majority of the fighting outside of Oregon came to a stalemate. There were only three real pushes that either side made in the summer months of the war. A United States force went north along the Red River to Winnipeg and laid siege to the city, but failed to capture it. The British, in turn, captured Sault Saint Marie in Marquette but failed to advance any further. In Maine, a combined land and naval attack under the joint command of General Winfield Scott and Commodore Matthew C. Perry advanced into New Brunswick. While Scott's advance stalled before it could reach Fredericton, Perry was able to lead a raid and bombardment of Saint John's. Perry had to retreat, however, when a British flotilla arrived south from Halifax to engage.
In Oregon, the summer months saw the most brutal fighting in the war. In June, President Polk and Congress passed a bill organizing any United States forces in the Oregon Country under Fremont. Fremont, commanding the newly formed Oregon battalion, moved north from Oregon City and in late July took Fort Vancouver after the short Battle of Bellevue, in which the 700 Americans and 400 local Chinook natives defeated the 300 British who were defending the fort. The Chinook had sided with the Americans after Fremont promised they could keep the lands they had settled on. Fremont continued north and rached the outskirts of Fort Nisqually by the end of August.
Aside from Fremont's campaign, Gilpin led forces from Forts Choteau and Bonneville along the north bank of the Columbia River to encircle Fort Okanogan. They reached the fort and surrounded it starting in early August. To cease supplies from reaching the fort, the soldiers attacked and fired upon any ships in the Columbia River that were heading for the fort. The small fort did not hold out for very long due to the lack of supplies and the men inside had surrendered by the end of the month. Meanwhile, a small British naval force on the Pacific began harassing shipping enterring the Columbia and bombarding Fort Astoria.