It could be interpreted in two ways depending on the intonation or punctuation.
The first sentence needs contextual information as it's missing who's going.
군대 간다는거 맞아. 그대들의 정신승리를 응원합니다.
=> Right, they are joining the military. I applaud their triumphant spirit.
군대 간다는거 맞아? 그대들의 정신승리를 응원합니다.
=> Are you guys really joining the military? I applaud your triumphant spirit.