According to the principles of retail strategy, how did sears once become the nation's biggest retailer?

After two decades of retail strategy, by 2004 Seers had recovered after suffering most compared to traditional retailer groups in the 1990s. By the end of 2004, Seers launched a new direction to merge with Kmart a discount retailed to create a $50 Bn plus giant under the control of, Ed Lampert, a former hedge fund manager.
The group is among the most significant "Broadline" retailers in the Us, but sales have lowered steadily after the merger.
The primary division of seers, the larger of the two brands sell a large selection of home appliances, automotive and apparels under a wide range of formats, i.e. General and discount department stores, specialized stores and several satellite units, for example, lands end and seers outlet stores.