What is the strongest check on the president's power ?

The President in the executive branch can veto a law, but the legislative branch can override that veto with enough votes. The legislative branch has the power to approve Presidential nominations, control the budget, and can impeach the President and remove him or her from office.

Explanation:

a drastic rise in oil prices ended decades of postwar.

the  seven  days  battles  were  a series of seven battles over seven  days from june 25 to july 1, 1862, near richmond, virginia,  during  the american civil war. the  seven  days ended with mcclellan's army in relative safety next to the james river, having suffered almost 16,000 casualtiesduring  the retreat.