Navigator: Stephen Baxter

Time's Tapestry III. As William the Conqueror's men attempt to bring an  end to the Murdrum, the furtive slaughter of  the English guerilla campaign against the occupying forces, a prophecy is spoken by a bedraggled woman in a shattered village - a prophecy that speaks of terrifying engines of war, engines of God's vengeance that will be unleashed in a war between civilisations. As the flame of the crusades burns back and forth across Outremer, as the Mediterranean becomes a crucible for a seemingly endless war between Islam and Christianity, as even Spain, where Moor and Christian had lived side by side the years being savage sieges, people die and families are torn apart to keep the prophecy alive. Will the engines finally win the war for Christianity or Islam?  Or will all be swept away by the rumoured might of the Mongols that have already swept through Asia. Or does the future lie not to the East, but to the West, across the great sea? And while the scholars debate the true nature of the prophecy, and Kings and emirs plot and conspire, all the time the engineers are working to build the engines of God. Where have the plans for these terrifying weapons come from?  What does the Weaver of Time's Tapestry intend?  https://cosmiccauldronbooks.com.au/products/weaver-stephen-baxter