spear·head 
(spîrhĕd′)
(spîrhĕd′)n.
1. The sharpened head of a spear.
2.
a. The leading forces in a military thrust.
b. The driving force in a given action, endeavor, or movement.
tr.v. spear·head·ed, spear·head·ing, spear·heads
To be the leader of (a movement, for example).