Rachel carsons book silent spring warned that one day few birds would be left to usher in the spring because of

Silent Spring is an environmental science book by Rachel Carson. The book was published on 27 September 1962 and it documented the detrimental effects on the environment of the indiscriminate use of pesticides. Carson accused the chemical industry of spreading disinformation and public officials of accepting industry claims unquestioningly.

In the late 1950s, Carson turned her attention to conservation, especially environmental problems that she believed were caused by synthetic pesticides. The result was Silent Spring (1962), which brought environmental concerns to the American public. Silent Spring was met with fierce opposition by chemical companies, but it spurred a reversal in national pesticide policy, led to a nationwide ban on DDT for agricultural uses, and inspired an environmental movement that led to the creation of the U.S. Environmental Protection Agency. 

the crusades are one of the most significant events in the history of europe and the middle east.   they were a series of religious wars carried out by christian crusaders from europe during the timeframe of the middle ages.   beginning in 1095 ce, the crusades saw european knights and noblemen travel to the middle east in an attempt to capture the holy land away from muslim people that had controlled the region for the previous centuries.   the term crusade means ‘cross’.   therefore, the europeans that became crusaders viewed themselves as ‘taking up the cross’.   in fact, many of the crusaders wore crosses on their clothing and armor as they made their pilgrimage to the holy land.

explanation:

the first forms of writing came from them in the form of pictographs around 3100 bc.