why did Fannin not aide Travis in San Antonio?

Answer 1

Appeals from Travis at the Alamo (via James Bonham) prompted Fannin to launch a relief march of over 300 men and four pieces of artillery on 25 February. Finally, after some delay, Fannin and his men moved out on the 28th for the ninety-odd miles to San Antonio. The entire relief mission was a failure. The troops barely had crossed the San Antonio River when wagons broke down, forcing the men to camp still within sight of Goliad. There was little or no food to take, some men were barefooted and overnight, the oxen to pull the wagons wandered off.
On 19 March, about 9:30am, Fannin began his slow retreat from Fort Defiance and destroyed everything he did not take with him. The column traveled about six miles when Fannin ordered a halt to rest his animals. At about 3:00pm Mexican cavalry appeared near Fannin's troops. The Texans immediately formed a hollow square with their wagons and cannon were placed in each corner for defense as Gen. Urrea's forces attacked. After a fierce battle that cost the Mexicans about 100-200 killed and wounded; Texan losses were seven to nine killed and sixty wounded, Fannin and his troops, facing overwhelming odds, surrendered at the Battle of Coleto. They were marched back to Fort Defiance and were imprisoned.
On 27 March 1836 Fannin's men were marched out in three columns and shot point blank and massacred. Fannin was shot before a firing squad while seated and blindfolded.

Answer 2

Yet it's the beleif that if Fannin HAD made it to the Alamo,those extra guns would have made the difference between defeat and victory.