Melissa Mohr tackles the modern origins of swearing is this great piece for Salon:

Bloody and bugger were the two most prevalent swearwords in the 18th and 19th centuries. There is ample evidence of their use, from multiple sources, because they were employed frequently (remember Shaw’s contention that bloody is “in common use as an expletive by four-fifths of the British nation”) and because they were considered less offensive than many other obscene words. It was possible to print the two, even if they had to be disguised as b——y andb-gg-r, where f——k would have been impermissible. But there is tantalizing, if sparse, evidence that our other modern swearwords were making the same transition at the same time, becoming not just obscene words but swearwords, used where one once would have used an oath. By the 1860s, swearing probably sounded much as it does today, with obscene words doing much of the work of swearing, and with religious words — damn it, Jesus, oh God — employed frequently but to less effect.”