[am-buh-skeyd] noun, verb, -cad⋅ed,
1. an ambush
–verb (used without object)
2. to lie in ambush.
–verb (used with object)
3. to attack from a concealed position; ambush.
1575–85; < MF embuscade, alter. (under influence of OF embuschier) of MF emboscade < OIt imboscata, fem. ptp. of imboscare, v. deriv. with in- of bosco wood, forest < Gmc *bosk- bush
Related forms: am⋅bus⋅cad⋅er, noun 
As used by Joseph L. Harsh in Taken at the Flood…
On this occasion, Jeb Stuart justified his reputation for alert reconnaissance. Almost instantaneously he perceived and reported to Lee the enemy’s rapid withdrawal. He also ordered Hampton to pursue and harass the Federal column retiring from Flint Hill toward the Chain Bridge. Into the hours of darkness, Hampton closely pressed the Federal tail under Sedgwick, lobbing shells into the panicky main body until the heavy casualties suffered by the 1st North Carolina Cavalry in an “ambuscade” laid by the 71st Pennsylvania Infantry bought breathing space for the retreating Federals. Meanwhile, in the center of the line, where Stuart had only Fitz Lee’s tired troopers, the Confederate horsemen pressed more gently and permitted Hooker to withdraw through the county seat virtually unscathed. Heros von Borcke, Stuart’s Prussian chief of staff (see his memoir online here), planted the Confederate colors on the courthouse green, while deliriously happy Southern sympathizers mobbed the troopers, and damsels showered Stuart with kisses. Jeb even found time to visit his friend and “spy” Antonia Ford. 
 ambuscade. Dictionary.com. The American Heritage® Dictionary of the English Language, Fourth Edition. Houghton Mifflin Company, 2004. http://dictionary.reference.com/browse/ambuscade (accessed: July 25, 2009).
 Joseph L. Harsh, Taken at the Flood : Robert E. Lee and Confederate Strategy in the Maryland Campaign of 1862 / [book on-line] (Kent, OH: Kent State University Press, 1999, accessed 25 July 2009), 19; available from Questia, http://www.questia.com/PM.qst?a=o&d=102364729; Internet.