As you can see in the birth rates per nation the most fertile countries are also the countries that are in developing process, or are very poor countries, developed countries have the lowest fertility rate from the list, in number one of the fertility list according to the Total Fertility Rate 2019 you will encounter Niger, with 7.153 children per woman, and in last place, according to the wolrd bank is Taiwan with 1.218.
Crises and alliances often bring about great moments in history, and one such example would be the alliance system that existed after German unification in the 1900s.