Why might congress and the people be more willing to allow a president to expand his powers during a time of national emergency? cite two instances when this has occurred?

The congress and the people allow a president to expand his power during a time of national emergency to keep the domestic peace, to wage war internationally and to stabilize the economy. The two examples are when president Abraham Lincoln receive retroactive permission to order the army increased from 22,000 to 75,000 to maintain domestic peace against internal rebellion and the other one is when the congress permitted Roosevelt to make a number of new agencies and organizations that issued principles and policies without regard to congressional mandates to stabilize the economy.