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Saint Patrick's color was blue, not green, say historians. The hue  St. Patrick's blue, a lighter shade  can still be seen on ancient Irish flags and was used on armbands and flags by members of the Irish Citizen Army, whose 1916 Easter Rising attempted to end British rule. But the use of green on St. Patrick's Day began during the 1798 Irish Rebellion, when the clover became a symbol of nationalism and the "wearing of the green" on lapels became regular practice. The green soon spread to uniforms as well. That evolution, combined with the idea of Ireland's lush green fields, eventually made blue a thing of the past.

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