Marshtide Watch is a Stormwind port outpost located in the Swamp of Sorrows. The watch was established to drive the Horde forces out of the swamp. The watch is manned by two companies of Stormwind Army soldiers under the command of Commander Joanna Blueheart. The Stormwind Navy makes use of the watch as a port in The Forbidding Sea. The watch is important both strategically and symbolically as it is the Alliance's counter to the orc town of Stonard, which is where the orcs first amassed their armies before attacking Stormwind in the First War.
Adapted from Wowpedia