Petty Officer 1st Class Michael Astorga crawls through a mud pit. Petty Officer 1st Class Michael Astorga, a hospital corpsman, crawls through a mud pit during a tactical combat casualty care field exercise at Naval Medical Center San Diego on Feb. 3, 2011. The exercise is a pre-deployment requirement. Those who pass the course will be trained in managing the most common battlefield combat injuries. SHARE: Download: Full Size (0.08 MB) Credit: VIRIN: 414319-M-WWD62-972.jpg Photo Gallery