frontier apparently gives a chance of out-flanking the French defences,
the fortress of Belfort, which was never reduced even in the war of
1870-1, was considered too formidable an obstacle against which to
launch an invading army. A rapid advance on Paris was therefore deemed
impossible if respect were to be paid to the neutrality of Belgium and
Luxemburg, and it was for this purely military reason that Germany has
to-day violated her promises to regard the neutrality of these states.
This was frankly admitted by Herr von Jagow to Sir Edward Goschen: 'if
they had gone by the more southern route they could not have hoped, in
view of the paucity of roads and the strength of the fortresses, to have
got through without formidable opposition entailing great loss of
time'.[8]

In the case of Belgium a very easy road was afforded into French
territory up the Valley of the Meuse, past Liège and thence into France
past Namur and through what is known as the Gap of Namur. A German army
could debouch into France through this gap the more easily inasmuch as
the French, relying on the neutrality of these two states, had not
strongly fortified the frontier from the sea to Maubeuge. Moreover, as
the country to the west of the Sambre was very easy country for
manoeuvring and furnished with good roads and railways, it was reckoned
that the formidable French lines to the south could be turned in this
manner, and the German army could march upon Paris from the north-east.

As to Luxemburg, plainly it could not in such a scheme remain neutral.
It would lie between the two wings of the German army, and controlling
as it did the roads to Brussels, Metz, and Aix-la-Chapelle, it could not
be allowed to cause such inconvenience as to prevent easy communication
between one portion of the German army and another.