There was a time when a C meant average. The average GPA at four-year colleges and universities has risen from 2.52 in the 1950s to 3.11 in 2006. And according to Stuart Rojstaczer, a former Duke University professor and founder of GradeInflation.com, GPAs only keep rising. At some colleges, Rojstaczer says, over 50% of the grades given are A's.
Trench warfare was caused by an advance in defensive weaponry. The machine gun was too heavy to be used as a mobile weapon, and therefore was placed into a fixed position. Barbed and concertina wire was also heavily used.
Machine guns were not mobile and chemical warfare was also not. However, another major cause was due to the equal forces gathered at the WESTERN FRONT. In August 1914, the German forces planned to invade France fast, before the Triple Entente could defend and then focus attacks on Russia (Schlieffen Plan).