Answer:
The given sentence is a simple sentence with a subject "They" and a verb "ate" in the past tense. The predicate of the sentence is "food provided by the military".
The phrase "provided by the military" is a participle phrase that modifies the noun "food". It provides additional information about the food that "they" ate. The participle "provided" is in the past tense and functions as an adjective modifying the noun "food".
Overall, the sentence means that "they" only consumed food that was given to them by the military.