Amerigo Vespucci said:Infantry weapons, sure. Tanks? Strategic bombers? Nuclear Weapons? No way.
Here's how I envision combat developing. Let's posit a conflict between Belgian Congo and German Cameroon in the early 1960s.
The terrain doesn't favor the introduction of the calvalrian armored car forces of either nation, so most of the fighting will be on the infantry level. Both German and Belgian troopers will probably carry submachineguns or the first-generation automatic rifles, which were developed in the late 1940s and early 1950s.
Airplanes, interestingly enough, would probably be used only in conjunction with artillery firebases, as spotters. They would be similar to OTL's OV-10s, except slightly less-advanced. Poison gas is a possibility, based on the Italian experience in Ethiopia. Without the experience of WWI, it's probably going to be used quite often in colonial conflicts.
Infantry combat will probably consist of poorly-trained local levies slugging it out with regular army support, usually in the form of artillery and gas. Imagine a Vietnam-style conflict without air power, fought soely by the ARVN (with American artillery) and the NVA. That's the sort of thing you could expect in colonial wars.
In places where the terrain allows, you might see the Guards or Royal Armoured Car forces coming out to play.
If we have a POD that eliminates the Dreadnaught race, you'll knock out a lot of military R&D, period. That would virtually eliminate prestige races for space and colonies, and create a more peaceful world.
If you have a POD where the naval arms races happen, it's eminently possible that competitions for prestige could result where nations compete for technological gains and multiple space races concurrently.
One aspect of that that might be interesting would be the development of an aerial arms race in the 1920s and 1930s. You could see larger and larger aircraft, a la the Dreadnaught/Battleship progression. That could result in increased aerial development, leading into a space race if conflict doesn't break out. Eventually, however, one side or the other is going to run out of money. That was the impetus behind the Washington Naval Treaty following WWI -- no one wanted to return to that costly Dreadnaught race.
Without a WWI, that Dreadnaught race may extend to bigger naval vessels, including aircraft carriers, or perhaps an air race by the 1930s. That's ignoring the financial situations of both Britain and Germany, however. France, Russia, and even the United States to some extent may be left behind in such a race.
I'm not sure the US would be left behind even back in 1900-1914 the British were scared that the US would get in a naval build race with them .