Green’s Dictionary of Slang

a burst of energy, a major effort; an attack; also attrib.

1967		M. Frayn Towards the End of Morning (2000) 16: I was going to have a blitz on the crosswords this afternoon.
1972		D. Pendleton Boston Blitz (1974) 28: The first little blitz you pull, cops are going to be converging on this town.
1996		J. Byrell Lairs, Urgers & Coat-Tuggers 282: George started off his one-man riding blitz by booting home Hopeful Venture.
1998		P. Cornwell Point of Origin (1999) 154: She did a blitz mailing.