Yes, the comma separates the dependent clause from the main clause. Athe comma use is correct here; comma use is a controversial part of English punctuation; there are many arguments, for example, about comma use in series—“the dog, cat, lamb, (?) and goat.” This is called the “Oxford comma,” and the debate about its necessity is ongoing in academic circles, with some disciplines and their journals endorsing it, and some condemning it. Other comma questions involve the oral pacing of a written line. But the sentence has other problems, notably the vague antecedents of the pronouns “he” and “his.” Are there two noblemen? Whose home is referred to? Is the castle and the house the same structure? Did the “approacher” exit? Etc. To repair the sentence, provide proper names to the actors in the sentence, or separate the clauses into two sentences and avoid the pronouns altogether. Also, “one of” is vague.