Definition of "spearhead"

Orion hit a rabbit once; but though sore wounded it got to the bury, and, struggling in, the arrow caught the side of the hole and was drawn out. […]. Ikey the blacksmith had forged us a spearhead after a sketch from a picture of a Greek warrior; and a rake-handle served as a shaft.

1879, R[ichard] J[efferies], chapter II, in The Amateur Poacher, London: Smith, Elder, & Co., […]

Spearheads of the NER bargain fares attack this year have been the introduction of weekend fares at a 7s 6d in the £ discount on ordinary rates between principal stations throughout the Region—[...].

1964 September, G. Freeman Allen, “Interim report on the East Coast Route express service”, in Modern Railways, pages 158–159

England played at a tempo in attack that was too much for Bulgaria, with width provided at various times by Walcott, Young and Stewart Downing and Rooney acting as the potent spearhead.

2011 September 2, Phil McNulty, “Bulgaria 0-3 England”, in BBC

Newcastle have put themselves within touching distance after a fantastic run which has been spearheaded by the goals of Senegal striker Cisse.

2012 April 21, Jonathan Jurejko, “Newcastle 3-0 Stoke”, in BBC Sport‎

George Monks spearheaded the project to solve this problem with a funicular, and work on the Lynton & Lynmouth Cliff Railway (L&LCR) began in 1887.

2021 January 13, Dr Joseph Brennan, “Spectacular funiculars”, in RAIL, issue 922, page 53