Why did so many germanic tribes begin invading the roman empire?

answer: what was the us involvement in ww1? although the u.s. tried to remain neutral when ww1 broke out, it finally joined on april 6, 1917 after declaring war on germany. the reason for america to become involved in ww1 was germany's unrestricted submarine warfare, which had already sunk several american merchant ships.

explanation:

c 3 branches because idk why they had 3 well when:

you think of it there are still contrys with 3