Why did great britain agree to pay the united states $15.5 million in damages after the civil war?

Great Britain paid damages to the United States after claims for damages on union ships by the Confederate Navy in ships that were built by the British. These are known as the Alabama Claims and were eventually decided in international arbitration in 1872 wherein Great Britain settled the matter by paying the United States 15.5 Million dollars and reestablishing friendly relations.

Is there not a question though?