As Bruce Springsteen lit up the stage in Manchester, England, with thousands singing along to a soul-stirring performance of Land of Hope and Dreams, the echoes reached far beyond the arena. Just as The Boss opened his run of shows with three bold messages about the state of the U.S., Kid Rock fired back from across the ocean, lashing out and telling Springsteen to “stay in Europe.” It was more than a clash of opinions—it felt like a full-blown storm between two icons, one singing for unity, the other shouting in defiance…