In 1975, McDonald's opened its first drive-thru window in Sierra Vista, Arizona, following Wendy's lead. This service gave Americans a fast, convenient way to procure a quick meal. The company's goal was to provide service in 50 seconds or less. Drive-thru sales eventually accounted for more than half of McDonald's systemwide sales. Meantime, the Happy Meal, a combo meal for children featuring a toy, was added to the menu in 1979. A period of aggressive advertising campaigns and price slashing in the early 1980s became known as the "burger wars". Burger King suggested to customers: "have it your way"; Wendy's offered itself as the "fresh alternative" and launched their "Where's the beef?" campaign. McDonald's sales and market still predominated, however.