"Old War" pensions were issued during and after the war for those soldiers and militiamen who were wounded or injuried in the line of duty. These men received monthly compensation for their injuries. The heirs of soldiers and militiamen received the half-pay of their loved ones for five years. This is also considered as "Old War" pensions.
"Service" pensions were issued after 1872 for those veterans still alive or their widows. Veterans could have served for as little as 14 days.
"Old War" pensions were issued in all of the early wars of the United States and does not pertain only to the War of 1812.