series of plans to attack the U.S. directly Imperial_German_plans_for_the_invasion_of_the_United_States series of plans to attack the U.S. directly Imperial_German_plans_for_the_invasion_of_the_United_States series of plans to attack the U.S. directly series of plans to attack the U.S. directly series of plans to attack the U.S. directly series of plans to attack the U.S. directly series of plans to attack the U.S. directly English series of plans to attack the U.S. directly English series of plans to attack the U.S. directly