What did the Prophet Muhammad (peace be upon him) teach about marriage for those who have gone to battle and have no wives with them?
      Narrated 'Abdullah:                          We used to participate in the holy battles led by Allah's Apostle and      we had nothing (no wives) with us. So we said, "Shall we get ourselves     castrated?" He forbade us that and then allowed us to marry women with     a temporary contract (2) and recited to us: -- 'O you who believe !      Make not unlawful the good things which Allah has made lawful for you,     but commit no transgression.' (5.87)