In the future, it would help if you told us exactly what is confusing you about the sentence. It’s in some sort of British English, and while I understood it right away, and recognize that it’s perfectly correct, it sounds rather odd to my American ear. Analysis: Sir: This is the person being addressed. We can ignore it in analyzing the sentence. That leaves us with: You will scarcely credit that it took six warders to dislodge him, three pulling at each leg. Vocabulary Scarcely: almost not, hardly Credit: to believe (from Latin “credere”) Warders: prison guards (“guards” in the latinized version of Germanic “warder”, via French) Dislodge: synonym depends on context Translation into standard non-British English: You will hardly believe (or "you're not going to believe") that it took six guards to dislodge him, three pulling at each leg. Grammar: You will hardly believe X, Y. X is a subordinate clause serving as a noun, the object of "believe". “You will hardly believe this fact. (This fact = “it took six guards to dislodge him.”) Y is a participle phrase, serving as an adverb to give additional information as to how the guards dislodged the man. A lot of information is omitted, since it would just be repetitive. Replacing the omitted information, we get: “three guards were pulling at each leg” (in order to dislodge him).

"that it took six warders to dislodge him" is a noun clause which is the object of "will credit".

1. 宾语从句 credit that....... 相信.... 2. take sb/sth to do sth 短语 3. 现在分词短语做状语： 一边三个人拖着腿