Answer:
The most important reason why Texans fought for the Confederacy during the Civil War was likely their commitment to the institution of slavery. Texas was a slave state, and many Texans believed that their economic and social well-being depended on the continued existence of slavery.
Slavery was a central issue in the Civil War, with the Confederacy fighting to preserve it and the Union fighting to abolish it. While there were other factors that contributed to Texans' support for the Confederacy, such as a sense of regional identity, opposition to federal authority, and a desire to protect their way of life, slavery was the underlying issue that drove their decision to fight.
It is worth noting, however, that not all Texans supported the Confederacy or slavery. Some Texans were Unionists who opposed secession, while others were abolitionists who opposed slavery. However, the majority of Texans at the time supported the Confederacy and fought in defense of the institution of slavery.