To put it simply, Kyoto was built based on chang'an but on a smaller scale.
Both cities have similar layout. At that time, the layout of Chang'an city is perfect for the purpose of Capital city in the aspect of it's defense and land division.
hope this helps
the year England declared war on France was 1939
There are more than three reasons why this happened of course but the best three are there they needed more land, resources, and some way to escape the cold.