Is it that in between the war of 1812 beginning and the US manufacturer expanding the exports to Great Britain increase

Yes, during the War of 1812, trade between the United States and Great Britain was significantly disrupted, leading to a decrease in exports to Great Britain. However, once the war ended in 1815 and tensions between the two countries eased, US manufacturers were able to expand their exports to Great Britain and other markets. This growth in exports helped to stimulate economic growth in the United States in the years following the war.