[Leaning Right]

an allied army of British, Prussian, and Dutch troops under Wellington’s overall command

Certainly the British and Dutch troops were under Wellington's command. But the Prussians?

[Sherman Logan]

Wellington’s army actually had slightly more Germans, from various states, than Brits.

Wellington did an amazing job, considering his polyglot army and being slightly outnumbered. He might very well have been screwed had the Prussians not showed up and piled into the French flank.