The Long War

continent-sized forest. From the air the Valientés saw it as a neat little rectangular patch etched out of the green, an oddly touching island of humanity all but lost in this global forest.
    But when you looked more closely you could see that it wasn’t humans who’d created the clearing but a party of trolls, under the direction of a human, labouring even as the passengers looked down on them, those massive muscles working under their black pelts.
    Bosun Higgs had proved to be a bright kid and surprisingly knowledgeable about the Long Earth – and the importance of the trolls. The big humanoids were ubiquitous, though not necessarily in large numbers. And they shaped the country they moved through, just on account of what they ate, pushed through, moved aside. In their ecological role they were like the big animals of Africa, maybe, like elephants or wildebeest. As a result, Helen learned now, the landscapes of the stepwise worlds, while quite unlike the Datum, were not quite like the Datum as it had once been before humanity either, not for a long time – because as mankind had risen up, the trolls had fled.
    Well, the working trolls below looked content enough. But their overseer carried a whip, as Sally quickly pointed out. Joshua suggested he only used it to make a noise, to attract the trolls’ attention.
    ‘Yeah, right,’ said Sally.
    Helen knew it was hard to tell how happy a troll was. You did hear of distressing incidents, such as the notorious case of the troll called Mary at the Gap, the case everyone was talking about, even the snobs aboard the Gold Dust . But you saw trolls wherever people were, working like this. They seemed to enjoy it. Of course if you pushed them too hard they could simply step away.
    Maybe they were just too useful to have a conscience about. Disturbing thought. And, as Sally said to Joshua, you wondered what they thought about humans.
    The party dropped off supplies for the logging team, and brought up samples of exotic lichen in little plastic packs, lichen taken from very old trees. Old trees were rare on Datum Earth and were becoming so even on the heavily logged Low Earths. That was the nature of the trade across the ‘Long Mississippi’, as Helen had learned the pilots called this stepwise route. Raw materials flowed in towards the Datum – timber, foodstuffs, minerals – but bulk goods mostly came from the Corn Belt worlds further in, and only rare or precious items were worth bringing in from beyond the half-million-step mark, such as unique old-tree lichens and other exotic flora and fauna. Indeed, Joshua suggested as they watched this trade proceed, their own community ought to think about exporting Hell-Knows-Where maple liquor. In exchange the Datum shipped out low-mass but high-tech goods, from medical kit to electrical generators, to coils of fibre-optic cable so the colonists could establish decent communication networks in their new worlds. It was the kind of trade that had always characterized the settlement of new territories, such as between Britain and its American colonies before the Revolution, with high-quality manufactured products being sent out from the homeland in return for raw materials. Helen’s father and his Footprint Congress buddies would probably claim it was exploitative. Maybe, but it seemed to Helen to work.
    And besides, whoever was ripping off whom, it had to be a good thing for this great river of airships to be linking all the worlds of mankind together. So Helen thought, anyhow.
    Twelve days out from Valhalla and they crossed a diffuse boundary into the Corn Belt, the great band of farming worlds a third of a million steps thick, stretching in towards the Datum from about four hundred and sixty thousand worlds out. The skies were a lot busier now, with twains like their own heading towards the Datum passing those heading back out, ‘upstream’, so to speak.
    The Gold Dust had made pretty fast progress to this point, but from now on the stops would be more frequent. There were waystations spread out stepwise all along the Long Mississippi, and further down the river geographically too, in many of these worlds. Helen was told that as they approached the Datum these stations would show up more frequently. At the waystations the twains stopped to take on cargo loads gathered here from the nearby worlds for collection. Sacks of corn were the staple export from these particular Earths, and the crews, with plenty of troll labour,