Final answer:
The Western Confederacy was defeated at various battles but officially ended with General Lee's surrender at Appomattox Court House on April 9, 1865. The take over of crucial territories like Vicksburg contributed to this defeat.
Step-by-step explanation:
The Western Confederacy was ultimately defeated at several key battles, but the definitive end came with the surrender of Confederate forces under General Robert E. Lee at Appomattox Court House in Virginia on April 9, 1865. Concurrently, General Ulysses S. Grant had been successful in his campaigns in the West, helping to secure Union control over important territories and waterways such as the Mississippi River. The capture of Vicksburg, Mississippi, was particularly crucial, as it split the Confederacy in two, giving the Union a significant strategic advantage. Further defeats, including the surrender of General Joseph E. Johnston's army in North Carolina, signaled the imminent collapse of the Confederacy, with the last significant Confederate resistance ending on April 26, 1865. Although General Stand Watie was the last Confederate general to surrender in June 1865, the fall of the Confederacy in the West was irrevocably sealed at Appomattox.