What action by hitler prompted great britain and france to declare war on germany?

The joint invasion of Poland by Germany and the USSR,

despite what people may think Germany invaded multiple smaller countries before invading Poland, it was a slow buildup but Poland was the last straw.

Explanation:

6 units. ab and lo are congruent sides, and if ab= 6 units, then lo would be the same.

1. it was caused by feudalism

2. charlemagne used christianity as a major cornerstone for his rule. cloisters were built all over the empire to act as centers for the (re)population of the vast european wilderness.

3. the europeans feared the next raid every time chetak

i'm not so sure about #6. but i hope i you with the first 3.