An Ice-Cream War is mostly set in the region that was British and German East Africa, across the span of World War 1. A lot of the book is centered around two brothers, Gabriel and Felix. Gabriel's in the British Army, and the war begins barely a week after his marriage to a young woman, Charis. Gabriel is sent to East Africa, and things are a complete mess. Felix is back home, just starting college, not at all sure of who he wants to be, and equally uncertain of himself as a man. He and Charis find each other, over a shared concern for Gabriel, and begin an affair, which ends badly, and prompts Felix to enlist and get himself posted to East Africa to find his brother.
On top of that, there's a whole subplot about an American, Walter Smith, who had a farm in British East Africa, only to have his land be the first, and practically only, place the Germans occupied. When they fell back, they seemingly stole his Decorticater (some threshing machine or something). The troops were commanded by his neighbor across the border, Erich von Bishop. So Smith becomes determined to find von Bishop and settle the score, assuming he can stay away from the local magistrate Wheech-Browning.
There's a strong undercurrent of what feels like absurdity to the book, mainly revolving around Smith. He's obsessed with von Bishop, who he's certain stole the Decorticater to use on his own farm. The fact von Bishop's native troops apparently defecated on every surface in the house when they left, and dug up his infant daughter's corpse, he brushes those things aside. But that piece of equipment, that's the important thing. Then there's the whole thing with Wheech-Browning being some sort of a jinx for an poor sucker around him and anything mechanical. Smith struck me as a stand-in for Americans in general: Maybe not a bad guy, but far more concerned with material goods than the suffering in war, so long as he could maintain a distance from it. When confronted with it, he's a sensitive, compassionate guy, but he does a pretty good job keeping away.
There's a lot in here about men and women. The expectations they place on each other and themselves. In most cases, the guys have an idea in their head of what their wife/lover is "supposed" to be like, and they don't much notice whether that's how she wants to be. For Charis, Gabriel doesn't seem to quite work for her as a sexual partner, and is largely oblivious to it (although he's struggling to understand his own turn-ons), and Felix isn't helpful from an emotional perspective. All of it is too new for him, which leaves Charis trying to find her own way through her doubts about herself, and her attempts to find an answer. With Smith and his wife Matilda, as well as von Bishop and Liesel, the women seem to have simply reached a point where they're determined to focus on their interests, and largely ignore their husbands' obsessions (although Matilda was such a space case I wondered if she was supposed to be suffering from some ailment). The husbands are simply too preoccupied to devote the kind of energy it would take to try and force Liesel or Matilda to give a damn, and so the ladies wait them out, then go on with their own interests as best they can.
'No bond exists between us, Felix thought. This existence had only driven them apart. Frearson took out his pipe and sucked at it noisily. The pipe was empty - everyone had run out of tobacco weeks ago. This was Frearson's particular habit that tormented Felic to a near-homicidal degree, like Gent's whistling or Loveday's schoolboy French. Felix realised, with something of a shock, that during his three-month spell in the "front line" he'd never seen a single enemy soldier. His animosities were all claimed by his colleagues.'