Great britain and france feared war was eminent with the annexation of

Czechoslovakia in March 1939

Explanation:

Britain saw that Hitler was lying in Munich Agreement when he agreed to not capture the remainder of Czechoslovakia.

Germany has violated the Treaty of Versailles by invading Rhineland (France) in 1936. With the annexation of Austria and the capture of the Sudetenland in 1938, to the control of Czechoslovakia in March 1939 and with the annexation of Poland on September 1939,  Britain declared the war against Germany after two days.

i confess that there are several parts of this constitution which i do not at present approve, but i am not sure i shall never approve them: for having lived long, i have experienced many instances of being obliged by better information or fuller consideration, to change opinions even on important subjects, which i once thought right, but found to be otherwise. it is therefore that the older i grow, the more apt i am to doubt my own judgment, and to pay more respect to the judgment of others.