Madmen of Mars by Erik Fennel

All this time we've kept quiet as a whole cageful of mice. And with good reason. During the Big Scare, while everyone was afraid that the Exclusion Ultimatum meant the Martians wanted an interplanetary war, the Earth Governments would have been only too ready to hang, shoot, stab, gas, electrocute, freeze, burn, poison, impale and/or defenestrate the dastardly culprits responsible. If they could have discovered who did what to whom. They didn't savvy Marties then—and still don't.

But we are lucky. The Marties never explained why they called home their Cultural Emissaries, abandoned space travel, cut off Luminophone contact and excluded Earthmen and Earth ships from Mars. They couldn't, because they themselves weren't sure what had happened. And amid the confusion on Earth the last Mars transit of the spaceship Banshee escaped official attention, which was largely due to Polly's good sense in making Mike see he'd better keep his big mouth shut. Our story would only have caused us trouble, even after the Scare died down.

All that was five years ago, but we still thought it best to keep still when this rather surprising diplomatic angling for resumption of Martio-Terran relations began just recently. The five of us were closer to what caused the Malignant Inertia Complex than all the big-name psychologists who have written books of wrong guesses since it disappeared, and we could see no danger of it starting up again. Mike was sure the Martian Thing had lost its grip. So we were willing to let the new treaty come up for a popular vote, as all interplanetary treaties must under the Earth Governments charter, without sticking our oars in or our necks out.