If my father hadn't died in the war, he would be over 60 now.
Literal
Father [subject-が] war-died had-not [if-たら], now [topic-は] 60-years [object-を] is-exceeding [explanatory-のだが].
A counterfactual conditional: ~していなかったら ('if he hadn't died') + ~ているのだが ('he would be..., but'). 戦死する is a formal compound meaning 'to die in battle.' The final のだが trails off with regret — 'but (he did die).'