If you have infantry forces without tanks/armored cars, even with modern equipment, radios, weapons, etc all you have is a replay of WWI. Sure modern medicine, personal equipment, rations, and so forth will make life more pleasant in the trenches, prevent illness and so forth but assuming both sides have equivalent equipment, and neither side has a major advantage in leadership, then you'll end up with a stalemate. Time on target, rolling barrages and good communications will help, but the other side will be able to respond as well. I don't see how you'll get to a war of movement.
In WWI once you stopped having a battle of maneuver and had tranches you basically had a stalemate. The better German tactics later on helped but were not decisive. The addition of the American economy and a million troops by fall 1918 when everyone else was pretty exhausted is what finished off the Germans. Absent an overwhelming manpower/equipment advantage, or exhaustion on one side versus the other, you end up with a stalemate. Modern equipment absent those bits that can turn a salient in to a breakthrough and war of maneuver...