the vanguard

劍橋詞典

the part of an army or navy that leads an attack on an enemy
先頭部隊(duì)，先鋒；尖兵
比較
rearguard

a group of people who lead the development of new ideas , or a leading position in the development of something
（思想的）先驅(qū)；領(lǐng)先地位
He is in the vanguard of economic reform . 他是經(jīng)濟(jì)改革的領(lǐng)頭人。
也見(jiàn) the forefront 返回 the vanguard