I believe it is marshy country around both Goliad and Refugio.
In the Texas War for Indepedence, there were battles at Goliad and Refugio. I went to school at the Catholic school, which had the Church where the battle was fought and still had bullet holes in the wall at that time.
The Texicans won the battles at both places but withdrew and then got lost. The Mexicans captured them and gave them no quarter as prisoners...
It most certainly is not marshy around Goliad nor Refugio. It is normally semi-arid.
I was an instructor in Kingsville (just south). It is known as the “desert by the sea”.