Many say it is probable that he was disgusted and sulky at having to rise so early, but this would hardly be a sufficient explanation.

The more probable conjecture is that, as he was on notoriously bad terms with the duke, he was willing that the latter should suffer a severe repulse at Minden, in the hope that he would be deprived of his command, and he himself appointed commander-in-chief of the allied army.
A few days after the battle, the exultation caused by the victory at Minden was dashed by the news that a Prussian army, twenty-six thousand strong, commanded by Wedel, had been beaten by the Russians at Zuellichau; and ten days later by the still more crushing news that Frederick himself, with fifty thousand men, had been completely defeated by a Russian and Austrian army, ninety thousand in number, at Kunersdorf, on the 11th of August.
At first the Prussians had beaten back the Russians with great loss.

The latter had rallied, and, joined by Loudon with the Austrian divisions, had recovered the ground and beaten off the Prussians with immense loss, the defeat being chiefly due to the fact that the Prussian army had marched to the attack through woods intersected with many streams; and that, instead of arriving on the field of battle as a whole, they only came up at long intervals, so that the first success could not be followed up, and the regiments who made it were annihilated before help came.
The news came from Berlin.

A letter had been received there from the king, written on the night after the battle.

He said that he had but three thousand men collected round him, that the circumstances were desperate, that he appointed his brother Prince Henry general-in-chief, and that the army was to swear fidelity to his nephew.