The Torah teaches that if a man marries a new wife he does not serve in the army for one year

Rav Eliyohu Gutmacher (In his Hagaos to Sotah 8:3) argues that it is clear that in this case, the man would be exempt from serving in the army since his remarriage occurred within one year of the time of his original marriage, which exempted him from serving in the army during that year on the condition that he is married, which he is once again. However, the S’fas Emes is uncertain about the law in this case, as perhaps the fact that he divorced his wife ended the one-year exemption to which he was entitled, and now that he is remarrying her, she is no longer a new wife who exempts him from army service. (R’ Ozer Alport)