Great Britain (especially 1840's-1850's) and Denmark (1860's) and yet little to no growth in the 20th century.

Your post is 100% spot on. WW1 was the "suicide of Europe". Before the war Europe had enjoyed basically 40 years of peace (yes there were conflicts in the Balkans) and had seen both a population & technological boom never before seen.

Guys who serve missions in Europe garner my respect. I knew one who serve in East Germany right after the fall of the Berlin Wall. Zero converts and he only taught five discussions his entire mission. Rough stuff.