The fifth day of the Siege of the Alamo, February 27th, was all about supplies and battlefield management. The Mexican Army ran out of supplies on this day and started foraging for food in the nearly deserted town of Bexar. When Bexar was emptied, the Mexicans began visiting nearby ranches and farms to impound food. The Mexican Army also dammed the eastern irrigation ditch that was the fort's primary water supply. Trenches were dug south of the Mission where there was very little cover to fire from. The Texians attempted to dig a new ditch from the cattle pen in the north-eastern corner of the fort, but the effort failed and compromised the wall at that point as well. Below is a diagram by Mark Lemon that more clearly represents the water situation in relation to the fort. Again, East is at the top.