Babbages Mechanical Computers have allowed scientists to solve the equations that allow travel to other worlds through the wall seperating them. Britain immediately dispatches a science mission to the world discovered now called "Eden". Limited by the constraints of Reality England waits to be open the doorway again and see the results of the science mission.
Meanwhile either through trade or espionage other countries throughout the world learn the methods by which Eden can be accessed.
The time for the weakening of the walls reoccurs and the British find their science mission under heavy attack by natives known as the Xorolunda. Pushing into Eden Lord Chelmsford first routs these troops then drives his forces deep into Xorolunda territory.
Losing patience, and wishing to leave behind an underling with whom he did not get on Chelmsford detaches his artillery under Major-General Summers and leaving him to catch up pushes on towards the Xorolunda main holding. Here his camp is attacked and overwhelmed, and although his subordinate Major General Innis manages to extricate the majority of the force Chelmsford is killed.
Pursued by Xorolunda, Innis falls back and his command is saved by the timely intervention of his now commander Summers and his artillery.
Retreating from Xorolunda territory however sits badly with Innis and his supporters, and eventually a bloodless mutiny takes place, with Innis and his troops forming an imperialist faction, and summers a preserver faction.