Yes trade purposes were indeed a reason for conquest and aggressive expansionI mean, there were several wars where tea was a factor. A few wars back during the period of colonization were fought to maintain tea being part of the trade that Britain was receiving, and the Boston Tea Party pretty directly escalated into the American Revolution.
As for wars fought entirely for tea, that I don't know if it happened for sure, but I really don't think it would just be off the table. Wars were started for less.
Spices are an example for this.