for example, upon reaching enemy territory, once the greek soldiers had been offloaded from their boats, their commanders would order the boats to be burned.

위에서 밑줄친 upon reaching enemy territory 를
1) as soon as ~
2) no sooner ~ 로 시작하는 문장으로 전환해주셨으면 좋겠습니다.

감사합니다.