The advance soon began; it was composed of six companies of the 60th Rifles, four companies of the 38th, and four of the 46th. These were to march by the canal, while seven companies of the marines moved along the railway embankment in company with the iron-clad train. The two parties were to join at the point where the canal and the railway approach closely to each other. The ground between the two embankments consisted of fields and marshy swamps.