The correct answer to this open question is the following.
The difficulties that people inside the Alamo faced were the fear, tension, and pressure of being besieged by the Mexican troops led by Mexican General Antonio López de Santana. The Mexican army had started to attack and bombard the Alamo site, and that is what William Barret Travis describes in his letter. He clearly established that nobody had been killed by then and although the Mexican General demanded surrender, Travis was not going to concede. Travis appealed to Patriotism, liberty, and courage to resist the Mexican attack.