The term 'REMEMBER THIS WHEN IN SAN ANTONIO' can be summarized by the crossword solution 'ALAMO', which is a five-letter word. The ALAMO is a former Spanish mission and fortress located in San Antonio, Texas. It was the site of a pivotal battle in the Texas Revolution in 1836, where a small group of Texan soldiers held off a much larger Mexican army for 13 days before being defeated. The ALAMO is now a popular tourist destination and a symbol of Texan independence.