In 1914, German strategic thinking derived from the writings of Carl von Clausewitz (1 June 1780 – 16 November 1831), Helmuth von Moltke the Elder (26 October 1800 – 24 April 1891) and Alfred von Schlieffen (28 February 1833 – 4 January 1913), who advocated manoeuvre, mass and envelopment to create the conditions for a decisive battle (). During the war, officers such as Willy Rohr developed tactics to restore manoeuvre on the battlefield. Specialist light infantry ("Stosstruppen", "storm troops") were to exploit weak spots to make gaps for larger infantry units to advance with heavier weapons and exploit the success, leaving isolated strong points to troops following up. Infiltration tactics were combined with short hurricane artillery bombardments using massed artillery, devised by Colonel Georg Bruchmüller. Attacks relied on speed and surprise rather than on weight of numbers. These tactics met with great success in Operation Michael, the spring offensive of 1918 and restored temporarily the war of movement, once the Allied trench system had been overrun. The German armies pushed on towards Amiens and then Paris, coming within before supply deficiencies and Allied reinforcements halted the advance.