The major global war that resulted in the extensive use of trench warfare and led to devastating casualties was World War I, occurring from 1914 to 1918. The war was marked by a devastating stalemate on the Western Front, where soldiers faced horrific conditions in trenches that spanned hundreds of miles. Innovations in military technology and tactics, combined with the scale of the conflict, resulted in unprecedented loss of life and reshaped the geopolitical landscape of Europe and beyond. The war's end set the stage for significant political changes, paving the way for future conflicts, including World War II.