I think that Great Britain was the most powerful European country in 1914. I base my opinion on the fact that they colonized much more land than any other country in Europe. Also on the world map of 1914 one can see that there is a lot more pink land (sybolizing British colonies) than any other color. They held control of Australia and Canada entirely, as well as India, and even some of Africa; that is a lot of land, and in those days, land meant power.