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I read a series of books where the aliens had two life stages. One stage was like us, physical. When they died they became some form of electromagnetic existence, or something like that. This second stage is how they communicate over very long distances. Because of this, their entire culture used only ceramic and plastics. A long war with us broke out by accident because on first contact we tried to transmit a message electronically. This resulted in killing their second stage fellow, which was interpreted as aggression, and we've been at war ever since. Also by accident one of their second stage fellow became trapped in one of our research facilities.
Over the years he comes to realize the truth of the accidental start to the war and decides to eventually show himself, which eventually results in the end of the war. The other books in the series covers their culture and our growing mutual economies, and political intrigues. Anyone know the title of this series?