USA military operations
The most successful large scale operation, perhaps ever, was the first Gulf War.
I have recently read that our strategy and prosecution of that war was mundane at best. The fog of war was palpable and the performance of our troops vs the Republican Guard was fairly even. We won handily based solely on superior tech.
I have long been fascinated by the success of the South African military group that was Executive Outcomes ltd. I am not a fan of privatized military but our success in Pakistan and the legendary success of EO ltd in using locals supplementing their forces seems to be the way to operate if you have no interest in acquiring new territory