Instacart, the fast-growing online grocery delivery start-up that can get groceries to your doorstep within an hour, is growing some more. The three-year-old company just announced it has raised $220m in a funding round led by the venture capital firm Kleiner Perkins Caufield & Byers.

The Army and Air Force Exchange Service - widely known as the PX or the Exchange - is designed to provide everything a soldier might need or want, tax-free and often at a deep discount: uniforms, tactical gear, recreational sports equipment, vitamin supplements, electronics, furniture, booze, lawn ornaments. It serves 12.8 million customers in 50 states and more than 30 countries. In fiscal 2013 the PX had revenue of $8.3bn and a profit of $332m. About a third of that was reinvested in operations, and the rest - $208m - was plowed into the Pentagon's morale, welfare and recreation programs to provide services like playing fields and on-base Boy Scout troops.

Four years ago, when its little card reader attachments for phones and tablets began to show up in cabs and at farmers' markets, Square was one of the coolest, most innovative companies in Silicon Valley. That's over.