Hiraheishi wa Kako o Yumemiru is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

It details the life of a mid-rank soldier who died at the very end of the war against the Demon Race. Fortunately for him, he wakes up to find that he’s a baby again, in the embrace of his real mother, years in the past.
Determined to avoid the chain of tragedies that took his beloved ones away from him, he takes advantage of the advancements in swordsmanship and magic that developed during the war (as we all know, wars are when many scientific breakthroughs tend to happen), and tries his best to prepare for the demon invasion as well as strengthen himself with maximum efficiency.