The money was not as important as the workers, thinkers, raw materials. The prior civil war era was a period of massive industrial output, despite the government simply throwing legal tender into circulation without obtaining gold from Europe, and the destruction of huge quantities of wealth in the war. The railroads and war effort required business to organize the transportation and production of large quantities of material wealth which lead to a greater focus on industrial profits, rather than hollow financial profits from real estate speculation. The later form of investment is 'hollow' because the procedure is a M -> M' paper gain which does not produce any material goods or fixed capital as a side effect.
European investors had been investing money in America since 1600s, primarily to engage in real estate speculation on western lands, what was important in industrialization is that there was a shift in investment from real estate speculation to industrial development. The driver of the shift was industrialists like Andrew Carnegie who were involved in the war effort.
To promote industrial investment without militarism it's primarily a matter of reducing large after-tax total returns and access to credit for financial speculators obtaining hollow M -> M' gains relative to industrial investors.