The French called it "rivière à la Grande Glaize" (later spelled as "glaise", meaning river of Great Clay), referring to the soil in the area.

It flows southwest to Wapakoneta, then generally north in a zigzag course, past Delphos, Fort Jennings and Oakwood.

It joins the Maumee from the south at Defiance, approximately 2 miles (3 km) east of the mouth of the Tiffin River at 41°17′13″N 84°21′23″W / 41.286893°N 84.356527°W / 41.286893; -84.356527.

Fort Defiance was constructed in 1794 near the confluence of the Auglaize and the Maumee by General Mad Anthony Wayne.

Fort Amanda, constructed along the river southwest of Lima in 1812, was an important American outpost during the War of 1812.