At the forefront of something. The lieutenant who was in the van of the assault, leading a small party of machine-gunners to clear a path for the rest of the infantry. The senator had been in the van of the movement to equalize pay for all citizens since the late 1960s.

Someone who drives a nondescript white van for work, especially one who drives in an aggressive, reckless, or dangerous way. Alludes to the perception that such drivers (typically male) are ignorant or rude. I used to cycle to work, but after nearly being knocked over three separate times by white-van men, I decided to start taking the bus.