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.
During trench warfare, opposing armies conduct battle, at relatively close range, from a series of ditches dug into the ground. Trench warfare becomes necessary when two armies face a stalemate, with neither side able to advance and overtake the other. Although trench warfare has been employed since ancient times, it was used on an unprecedented scale on the Western Front during World War I.