Cassel was fortified with a circuit of walls at around this time .
Cassel was suffered its own decline , which was reflected in its loss of status as a regional capital ; Tournai took over as the capital of the newly constituted Civitas Turnacensium .
Cassel was fortified with a circuit of walls at around this time but suffered its own decline , which was reflected in its loss of status as a regional capital ; Tournai took over as the capital of the newly constituted Civitas Turnacensium .