Under the leadership of General Santa Anna, the government of Mexico was transformed into a military dictatorship, ignoring the Constitution of 1824. 

The state of Coahuila did not cooperate with Santa Anna's plans, and the state of Zacatecas rebelled, but was brutally crushed by the military. 

One of Santa Anna's "reforms" was to reduce the number of the militia to one soldier for every five-hundred inhabitants, and to disarm the remainder. This arbitrary decree was a sufficient justification of Texas for her subsequent acts.

Every one who knows the Texans, or who has heard of them, would naturally conclude that they never would submit to be disarmed. Any government that would attempt to disarm its people is despotic; and any people that would submit to it deserves to be slaves! (Yoakum)

As Mexican troops began pouring into Texas, the people of Texas turned violently against Santa Anna. 

William B. Travis' letters sang of "the hour that will try men's souls." Stephen F. Austin spoke that Santa Anna was destroying the people's rights, and Texans "would resist and repel" "any armed force" sent against Texas.

As unrest increased, Santa Anna's soldiers began confiscating weapons, searching houses, disbanding suspicious groups that re-formed as fast as they were broken up.

A number of soldiers marched to Gonzales to confiscate a small cannon given them years ago to ward off Indians.

The Gonzales alcalde received the order to surrender the cannon, but stalled for time, sending runners to the surrounding area for armed assistance.

Not long after, the Texans shed all pretense of ever surrendering the cannon, and delivered the message to the Mexican army: "I cannot, nor do I desire to deliver up the cannon...and only through force will we yield."

Word of the impending conflict reached Stephen F. Austin, who sent letters calling for volunteers to go to Gonzales, noting that "The present movements of the people of Texas are of a popular and voluntary character, in defense of their constitutional rights," and that the people would "defend themselves and the constitution, if necessary. 

Austin continued "... [T]he position taken by the country up to the present time, is purely defensive," and, Texans should "avoid making attacks unless they should be necessary as a measure of defence."

Eighteen men in Gonzales, willing and able to conduct an organized fight, removed all boats from the Guadalupe River, and hid the ferry in a bayou north of town. 

Volunteers responding to the call to arms rushed to the scene, and the little Texan force of 18 mushroomed to 167 by October 1.

During this time, Sara Seely DeWitt and her daughter Evaline made the first Come And Take It flag. It was Texas' first battle flag, and first lone star flag.

[To my knowledge, it is also the only flag that indirectly equates arms to liberty, and that openly defies a tyrant's attempts at gun control. Ed.] 

From across the Guadalupe river, the Texans dared the Mexicans to "Come and take it!" echoing the words emblazoned on their newly created flag.

The Texans expected the Mexicans to attack at any time, so they decided to strike first. 

The night of Oct 1 the Texans crossed the river and opened fire on the Mexican troops at first light on Oct 2, sending the troops hurrying back to Bexar, without the cannon.  (sources)