Definition of "quagmire"

Never did I see a more dreary and depressing scene. Miles on miles of quagmire, varied only by bright green strips of comparatively solid ground, and by deep and sullen pools fringed with tall rushes, in which the bitterns boomed and the frogs croaked incessantly: miles on miles of it without a break, unless the fever fog can be called a break.

1886 October – 1887 January, H[enry] Rider Haggard, She: A History of Adventure, London: Longmans, Green, and Co., published 1887

"And what was this, my beloved brother, but a vain yielding to unbridled imagination, which, like a spring confined to one spot, collects its pure clear waters, and in at once a beauty and a blessing; but which, allowed to spread abroad in every direction, oozes through the marshy earth, becomes stagnant, and is habited by the loathsome reptile. That which would have been a green haunt, with its fair fountain, is a dreary and useless quagmire. Is it not thus with the mind, Guido?"

1834, L[etitia] E[lizabeth] L[andon], chapter I, in Francesca Carrara. […], volume I, London: Richard Bentley, […], (successor to Henry Colburn), pages 168-169

I’ve had my doubts about Daenerys’ ability to rule, inspired in part by the quagmire in Meereen. Still, this feels like a precipitous decline. The queen of sobriquets has always been power hungry.

2019 May 5, Danette Chavez, “Campaigns are Waged On and Off the Game Of Thrones Battlefield (Newbies)”, in The A.V. Club‎, archived from the original on 28 January 2021

The only way to know Shakespeare is through his works, and his works are textual quagmires.

2021 November 24, Stephen Marche, “The Algorithm That Could Take Us Inside Shakespeare’s Mind”, in The New York Times‎