That's an extremely broad question seeing as you don't specify a time or place. As a general rule over time the amount that armies have used such methods has declined. Its important to distinguish that there are several variations in methods by which an army could gather materials from the territory its in. Firstly small forces and ones that are stationary or moving reasonably slowly in ancient times could often gather a certain amount of food via fieldcraft. Gathering wild edible plants, hunting and fishing as well as getting other basic materials like fire wood. Secondly they could buy the goods, if they wanted to maintain good relations with the locals they could make this entirely fair and market value but if necessary there could also be what might be more termed as "forging" where the goods are seized forcefully but not necessarily violently, potentially some compensation might still be given but its not necessarily market value and the goods are taken rather than voluntarily sold. Lastly you have full on pillaging which implies a certain level of greater violence than forging as well as suggesting the army is taking more than just basic goods like food but more goods that are easily transportable and valuable such as money, jewellery. It may also involve the murder or enslavement of civilians, rape and the purposeful destruction of homes and other property like burning and salting fields.