the vanguard
noun [ S ] uk/ˈvæn.ɡɑːd/ us/ˈvæn.ɡɑːrd/
先头部队，先锋;尖兵
the part of an army or navy that leads an attack on an enemy
Compare: rearguard
（思想的）先驱；领先地位
a group of people who lead the development of new ideas, or a leading position in the development of something
He is in the vanguard of economic reform. 他是经济改革的领头人。
See also: the forefront