Sentence:  “… This is a surprise attack, and I'd no wish that the garrison, forewarned, should escape. I am sure, Lord Stranleigh, that he has been descanting on the distraction of the woods and the camp, or perhaps the metropolitan <WSD>dissipation</WSD> of Philadelphia, …” 
Meaning of the word marked with <WSD> tags:  A dissolute course of life, in which health, money, etc., are squandered in pursuit of pleasure; profuseness in immoral indulgence, as late hours, riotous living, etc.; dissoluteness.