well good question. I am a muslim and i believe that ALLAH is the most powerfull and ALLAH created all of us. so ALLAH, when created this world and everything and ALLAH gave Holy Book "QURAN" to obey . and tell us in QURAN that whats wrong and whats correct. so this is the rule of world that if there is good things happen then there is also bad things will happen. now i m going to move on ur question that why ALLAH not save us in bad (War ) conditions.
ALLAH give us full authority to live our life . now its our decision that we do right or wrong things. in war most of people are innocent who killed so ALLAH told us in QURAN that innocent are free from any punishment . if a child born and after born suddenly he died then what u think that ALLAH will send her or him in HELL or HEAVEN???? offcourse in HEAVEN bc he is innocent. but no one knows that why ALLAH born him and suddenly take away from world . for example , very very general exampe of our daily life. the owner of PEPSI will never tell the secret how to make pepsi. so now tell me there are millions of animals , humans and other things but why ALLAH created an "Aunt" ? no use of Aunt in our life but why ALLAH created trhgem... these all are the secrets and only ALLAH knows their secrets . so if any boy killed in war then it doesnt mean that he is bad or good thats why he killed it means that his life decided by ALLAH is finished.
RE: Eid ul Azha
KHER MUBARAK! and same to u and to all muslims around the globe