Bradford Walker has more information on the relatively obscure Fang of the Sun Dougram, the “lost” inspiration to BattleTech:

It is a happy accident that the people behind BattleTech put in all the hard SF that they did, from technologies to politics, because it turns out that Dougram itself is a nigh-seamless fit into the overall feel of BattleTech. You could set this story in the Free Worlds League and make only one change (Earth to Atreus, and associated references) to make it fit–it’s that good a pre-existing fit. That’s why I’m recommending the series, old as it is (early ’80s), to those wanting something Japanese for their BattleTech/Real Robot fiction-or-gaming inspiration.

The series never got a Western release, so–like Legend of the Galactic Heroes–you’re going to have to rely on fan-curated playlists and grey streaming sites to actually watch the damned thing. It’s not in HD, the animation is akin to what you saw in the original Mobile Suit Gundam and other anime series of that era, and it’s got that 80s malaise that’s common to anime of the era, but the story is solid and worth your time.

I’ve wanted to watch this show for a long time… and there it is, right there on YouTube. You can actually see the real thing, without it being butchered for the American market like that other mecha series was. The military scenarios are far more believable than, say, Dana Sterling and the Southern Cross. There’s a grittier tone reminiscent of Firefly’s “The Train Job” episode. And of course, you get to see what they call a ShadowHawk in BattleTech whoop up on some Griffins.

With helicopters transporting mecha to the battlefield, a winch being used to pull a BattleMech up a cliffside, and even an over the top grappling move that takes a mech’s arm off, this is nothing like the tabletop games I played back in the day. But the storytelling is far more coherent than anything in the Robotech series– and the narration occasionally borders on the poetic. Plus, the songs are way better than anything Minmay ever did. I’m hooked!