In the campaign of 1757, Frederick, marching to the conquest of Bohemia
with two armies, which had each their separate line of operation,
succeeded, notwithstanding, in uniting them in sight of the Duke of
Lorraine, who covered Prague with the imperial army; but his example
should not be followed. The success of this march depended entirely on
the inaction of the duke, who, at the head of seventy thousand men, did
nothing to prevent the junction of the two Prussian armies.