The Russian Revolution of 1905 had its roots in . World War I
economic and political issues
the discovery of vast oil fields
Russo-Japanese War

Russo-Japanese War

Explanation:

the russo Japanese war

the group i'm selecting: greeks.

a first group of greek immigrants came to the us in the 1850s. the second group came to america starting in the 1890s due to economic opportunities they didn't have back in their home caused by the hardships of ottoman rule. greek immigration was 90% male, many of them expected to work and return to greece after earning enough capital, but ultimately had to remain in the us after the greek genocide.

the deaths of over a million communist soldiers

post-traumatic stress disorder in veterans