Sentence:  Colonel Frederick W. Lander , impersonated , will again make his break-neck ride down the steep declivity of Talbott 's ( now College ) Hill and thunder across the bridge to <WSD>join</WSD> Colonel Benjamin F. Kelley 's ( West ) Virginia Infantry , then swarming through the streets in pursuit of the retreating Confederates . 
Meaning of the word marked with <WSD> tags:  become part of; become a member of a group or organization