Ambuscades
--A Northern dispatch from Alexandria says:‘ It is ascertained as a fact that the Confederates were kept well informed of all the arm- movements; and their gradual withdrawal from Fairfax and other advanced posts was a portion of their plan in drawing the Federal troops into their ambuscades. Hence the imperfect condition of their earthworks at Fairfax and other points, which excited ridicule among our military men.
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