Eagles are master hunters, Osprey consummate divers. Both are Apex predators. When they meet, and decide to engage each other, it is really a spectacle and either can win.
First a note, this was high in the air and constant agile flight. They were all over and I just tried to capture as much as I could, quality was secondary. They were too high for that. In general I was spinning around hoping to catch as much as possible.
The Osprey came at the Eagle from above, hitting him in midair. He never saw him coming. Both have nests nearby, but the Osprey wanted the Eagle to stay in his own space.
Once the Bald eagle was hit he went into an attack to protect himself. Bald Eagles have the ability to fly upside down for a moment. Osprey do not.
The Eagle went on the attack and chased after the Osprey. Now they were moving away from the nest, so it might have been part of the protection plan.
In the above image you see the Eagle again on the defensive after the Osprey spun around him in the air. It looked like this Osprey was much more agile. He also had advantage of being above, where he could dive.
The Eagle was determined to not to turn his back of the Osprey. He continued flipping upside down. Osprey talons are probably the only other birds that rival an Eagle.
Finally the Eagle had to turn down in order to continue flying, the Osprey maintained the advantage by easily floating above the Eagle. Osprey fish and hunt by keeping stationary in midair. He used it here.
The Eagle continued turning upside down to keep the Osprey away. Above was the last turn with the Osprey circling up higher.
Finally they moved down the marsh watching each other, but the Eagle was being moved away from the Osprey nest, the intention all along.
The Osprey had successfully protected the nest. We standing close to it and looked to be empty. Perhaps eggs were there, we saw no young.