Final answer:
One strategy that helped the Union win the Civil War was destroying Confederate supplies through Sherman's March to the Sea, which decimated resources and morale in the South. Coupled with major victories and superior industrial and manpower capabilities, the Union pressed their advantage to ultimately compel Confederate surrender.
Step-by-step explanation:
The strategy that helped the Union forces win the Civil War was destroying Confederate supplies to convince Southerners to give up. The Union implemented a total war strategy under the leadership of General Sherman, whose March to the Sea through Georgia destroyed everything in its path. This scorched earth policy, coupled with significant battles such as the Union's victory at Vicksburg, which gave them control of the Mississippi River, and the defeat of Lee at Gettysburg, crucially undermined the Confederate’s ability to sustain the war.
In contrast to the Confederacy's lack of a strong navy and their emphasis on defending territory, the Union used its larger population and industrial advantages to conduct offensive operations and maintain long supply lines necessary for their large-scale campaigns. The North, with its greater industrial capabilities and extensive railroad grid, was far better equipped to mobilize men and maintain the supply chains required for continuous warfare.