"Brief Histories of the Golden Dawn"

[Here] are a few links that detail some of the Order's history. For more detailed information the books of R.A. Gilbert, Francis King, Ellic Howe, Ithell Colquhoun, Israel Regardie, and Mary K. Greer (and the pamphlets edited by Darcy Küntz) are worth acquiring (noting that many of the above are out of print, and therefore fetch a hefty price on the second-hand book market).

Firstly there is the History Lecture that was written by Westcott. It offers an interesting look at the Order, although it can hardly be classed as factual. Nevertheless, this is what many of the original members were presented with (and most likely believed):

HOGD History Lecture

Below is an essay that the Ciceros wrote on the history of the Order, much of it included in their book, The Essential Golden Dawn (which I personally recommend to those who know little or nothing of the Order, its history, practices, and so forth). While some information is now outdated, I have yet to find a freely available essay on the history of the Order that is as clear and comprehensive:

HOGD Ciceros History

Finally, another website I came across that has a detailed breakdown of the timeline:

'Detailed' History of GD