Texas Independence Day is the celebration of the adoption of the Texas Declaration of Independence on March 2, 1836. The declaration was literally produced overnight! It's urgency was paramount because while it was being written, the Alamo was under siege by Santa Anna's army of Mexico. With this document signed by 59 people, settlers in Mexican Texas officially broke from Mexico creating the Republic of Texas!
".... We, therefore, the delegates with plenary powers of the people of Texas, in solemn convention assembled, appealing to a candid world for the necessities of our condition, do hereby resolve and declare, that our political connection with the Mexican nation has forever ended, and that the people of Texas do now constitute a free, Sovereign, and independent republic, and are fully invested with all the rights and attributes which properly belong to independent nations; and, conscious of the rectitude of our intentions, we fearlessly and confidently commit the issue to the decision of the Supreme arbiter of the destinies of nations."
-The Texas Declaration of Independence