What is mercantilism and how did European countries like Spain use it to their benefit (positive gain)?

they kept back from the wars and didn't want any action meaning wars.

although world war i began in 1914, the united states did not join the war until 1917. the additional firepower, resources, and soldiers of the u.s. to tip the balance of the war in favor of the allies. remaining neutral. when war broke out in 1914, the united states had a policy of neutrality.