But this was not Frederick's idea.
As spring approached, he had been busy redistributing his troops from their winter cantonment, and preparing three armies for the invasion of Bohemia.

April had been a busy month for the staff, and the aides-de-camp had passed their days, and even their nights, on horseback.
At last all was in readiness for the delivery of the stroke, and on the 20th the king started from Lockwitch, facing the old Saxon camp at Pirna; the Duke of Bevern from Lousitz; and Marshal Schwerin from Schlesien; and without the slightest warning, the three great columns poured down into Bohemia.
The movement took the Austrians absolutely by surprise.

Not dreaming of such a step on Frederick's part, they had prepared, near the frontier, vast magazines for the supply of their advancing army.

These had to be abandoned in the greatest haste, and a sufficient amount of food to supply the entire army, for three months, fell into the hands of the Prussians.

Marshal Browne and General Konigseck, who commanded the Austrian armies in Bohemia, fell back to Prague with the greatest speed that they could make.
The light irregular corps, that Frederick had raised during the winter and placed under experienced and energetic officers, pervaded the whole country, capturing magazines and towns, putting some to ransom, dispersing small bodies of the enemy, and spreading terror far and wide.