How would you translate an expression like "would become"?

Question

I was recently assigned to write about the Franco-Prussian War, and wanted to write at the end that "German strength and French revanchism would become causes of World War I." How would you translate this "would become" into Russian? I thought of either "стали" or "станут", but this doesn't seem to be an exact translation of forms like "would become".

Answer 1

Well, by meaning it's something like:

Немецкая мощь и французский реваншизм впоследствии станут причиной Первой мировой войны.

or

Сила немцев и реваншизм французов в итоге станут одними из причин Первой мировой войны.