On April 30th, 1975 the invasion force of the communist of North Vietnam flooded the cities of South Vietnam, the Junior Military Academy was no exception. This day marked the darkest day in Vietnam history, and it also was the end of an era. The last battle was fought here and the last national anthem was sung here while the junior cadets lower the national flag. T'he country was in the state of anarchy while everyone was scrambled trying to get out of the country and of the persecution from the enemies, a handful of cadets, some of them as young as 12 years old decided to stay on to protect their school. They were no match for the communist forces, but their actions has shown the world the bravest tradition of these "thieu sinh quan". This has become the legacy of the academy. More information can be found on the net or on the link on anhusa's link.
Reference:
Audio clip about this story (in Vietnamese): Tran Danh Cuoi Cung - nha van Dao Vu Anh Hung.
http://www.freewebtown.com/quy161/VNCH/Baiquoccacuoicung.htm

Article about this story in Vietnamese, hopefully someday I wll translate it to English:
The bloody defense of the Junior Military Academy on April 30th, 1975