Use of artillery shells was dictated much by the capabilities of the howitzers from which they were fired as by the projectiles themselves. Howitzers firing on a high arcing trajectory were able to drop explosive shells into dead ground and defended enclosures. The combination of howitzer and shell was less useful in a battle of manoeuvre, where mobile formations did not present a suitable target and could be attacked more effectively with round or caseshot. However, in battles like Waterloo, where the defenders had tied themselves to a hilltop position, the allied formations sheltering on a reverse slope would have been vulnerable to shellfire, while both the defenders and fabric of the defended farms of La Haye Sainte and Hougoumont were also vulnerable to the fragment and flame of shell exploding shells.