The federal legislature or congress can repeal the state laws under the necessary and proper clause in order to impose federal laws necessary to provide general welfare and common defense of the nation because they have the authority to do so. This authority was given to them because the people believed that the congress would decide for the common good.
Moreover, only the federal legislature has the right to contract debts, lay taxes and if they believed that a state law may prevent the collection of a federal tax, then they can repeal state laws making sure that it is for the benefit of the United States.
The most main reason was the christian wanted to take over the Jerusalem from the Muslims and they also believed that if they fight their sins would be wiped out. <span />
One of the benefits of the new suburban lifestyle of the 1950s was that people had far more property, and therefore had more space. In cities, it would have been impossible to have the types of yards and garages seen in suburbia.
Which war are we talking about?