Alizon and Serrin
Alizon, with exclusive access to the globe manufacturing facilities in Welltower, has by far better technology than Serrin, which still depends largely on fossil fuels. They have let Serrin have some of their tech but not all of it. Serrin, jealous of Alizon's success and fearful of attack, tried to attack Alizon with a surprise missile strike in the Rebound War. This attack was foiled by the Aers and led to the utter destruction of most of Serrin's capital city and military fortifications.
Two wars between Alizon and Serrin are described in the books.
18 Years Ago
The Rebound War lasted a few days and included three attacks: a bomb from Serrin causing the Flood in Welltower; a raid by Alizon on Serrin in which Aer (father) and Aer (son) were rescued; and a missile strike from Serrin which was deflected by a force shield, causing all the conventional explosives and power grids in Serrin to explode, nearly destroying the entire nation.
- Bk. 2 Ch. Borders. "Their equipment, as best we know, is nowhere near as advanced as ours. A lot of their technology came from us but they don't know how to use it as well. We keep the best stuff for ourselves."
- Bk. 2 Ch. Borders. "That area used to be called the Outer Reaches, back before it was given in treaty to the other side."