This analysis reports the effects of extreme temperatures (temperatures exceeding 100 degrees F) on the hydration of infantry-men conducting stability and support operations during phase IV Operation Iraqi Freedom in the months of June and July 2003 in An Nasiriyah, Iraq. Fifty-three infantrymen were evaluated for signs of dehydration after completing questionnaires regarding their activities during the previous 24 hours. We conducted an analysis comparing these activities and their state of hydration. The most significant factors contributing to dehydration in extreme environments proved to be the individual's level of exertion and exposure to the sun while levels of water and caffeine consumed showed no correlation to one's level of hydration. We conclude that integrating a proactive, field-expedient means to monitor a unit's level of hydration can increase the combat effectiveness of units in training and combat alike.