Prince of Prussia, Frederick William, would command the army now
mustering in the Palatinate, largely composed of South Germans, sent a
thrill of joy through those States. Taught by the folly of her
stay-at-home strategy in 1866, Bavaria readily sent her large contingent
beyond the Rhine; and all danger of a French irruption into South
Germany was ended by the speedy massing of the Third German Army, some
200,000 strong in all, on the north of Alsace. For the French to cross
the Rhine at Speyer, or even at Kehl, in front of a greatly superior
army (though as yet they knew not its actual strength) was clearly
impossible; and in the closing hours of July the French headquarters
fell back on other plans, which, speaking generally, were to defend the
French frontier from the Moselle to the Rhine by striking at the
advanced German troops. At least, that seems to be the most natural
explanation of the sudden and rather flurried changes then made.

It was wise to hide this change to a strategic defensive by assuming a
tactical offensive; and on August 2 two divisions of Frossard's corps
attacked and drove back the advanced troops of the Second German Army
from Saarbrücken. The affair was unimportant: it could lead to nothing,
unless the French had the means of following up the success. This they
had not; and the advance of the First and Second German Armies,
commanded by General Steinmetz and Prince Frederick Charles, was soon to
deprive them of this position.

Meanwhile the Germans were making ready a weighty enterprise. The
muster of the huge Third Army to the north of Alsace enabled their
General Staff to fix August 4 for a general advance against that
frontier. It fell to this army, under the Crown Prince of Prussia,
Frederick William, to strike the first great blow. Early on August 4 a
strong Bavarian division advanced against the small fortified town of