How does organizing the past by period differ from organizing the past by theme?

The answer is athens and sparta.

Try a? sorry if i’m wrong

Agreat cause of former hostility was caused when the invasion of north europe was invaded by germany and when the devestation of pearl harbor have occurred during world war ii followed by the axis powers; because of the damage created by the axis powers, both nations in europe and the united states grew hostile and grew further alliances with more  nations in europe to work along side together to oppose the axis powers.