Although the term 'Britishness' " into political and academic prominence" only in the late 20th century, its origins lie with the formation of the Kingdom of Great Britain in 1707. It was used with reference to Britons collectively as early as 1682, and the historian Linda Colley asserts that it was after the Acts of Union 1707 that the ethnic groups of Great Britain began to assume a "layered" identity—to think of themselves as simultaneously British but also Scottish, English, and/or Welsh. In this formative period, Britishness was "closely bound up with Protestantism". The "Oxford English Dictionary Online" dates the first known use of the term Britishness to refer to the state of being British to a June 1857 issue of "Putnam's Monthly Magazine".