More tanks is one of the lessons of the lines.
1917, ARRAS .-- The Somme fighting ends.

Again our armies are built up, until the 760,000 point is reached.

FRONT, increased to nearly 120 miles by a relief of French troops, falls again to 105, owing to the German retirement about ARRAS.

Heavy guns have increased from just over 300 to 1,500.

Again our armies are ready, and the Battle of ARRAS opens the ALLIED SPRING OFFENSIVE.