John Foxx, who was the lead singer, front-man, and main song-writer for Ultravox before he ditched the band, left it in the hands of Midge Ure (who took it to considerable commercial succes) has said of "Hiroshima Mon Amour" on their 1977 album Ha! Ha! Ha!, that it was the first synthpop song in history and that he thought nobody else had done a song like that before. Of course, Foxx was a strange guy. A former hippy and mod kid, he decided and declared his intention to live a life without any emotion in the mid-70s. He wrote that sentiment into the track "I Want to Be A Machine" on Ultravox!'s first album. A huge fan of J.G. Ballard, and grandiosely imaging himself as the "Marcel Duchamp" of electronic music (at a time when Kraftwerk was about the only game in electronic music town) he is known for being rather influential, even as he was never actually very popular.
I'm a fan, of course, of some of his early Ultravox work and especially his first solo album, Metamatic from very early 1980 (literally just squeeks into the 80s by less than three weeks) and I've talked about both here before. Ironically some of his imitators (like Gary Numan) who were very upfront about citing the John Foxx era Ultravox as one of their main inspirations, went on to not only precede Metamatic, making it sound almost like a copy-cat (ironically) as well as achieving considerably more mainstream success and attention. Foxx's declaration might have been a bit self-serving; synthpop certainly evolved out of a collage of experimental electronic music experimentation going on all over the place in the 70s. Brian Eno, Kraftwerk, Tomita and Giorgio Moroder had been kicking around for years making pop music with minimoogs and other early synthesizers that are not really very distinguishable from synthpop. OMD ditched their guitars in 1975 (although they didn't release anything early enough to beat Foxx, I suppose.) When exactly did some early pioneering electronic pop music cross some arbitrary line to become synthpop? I dunno, but according to Foxx, and many in the music press accept this, "Hiroshima Mon Amour" was when this happened.
If so, it's probably a little bit belated of me to actually put this one up. Sure, it came out before the 80s, but it was the root of the 80s sound in many ways. It's actually a bit poppier than even stuff that came out later and was more popular—Gary Numan's work in particular (as well as Metamatic and some early Human League, for example) was really cold, distant, and cyper-punk-like.