Schliemann dug up the citadel of Troy, but destroyed most of the site, including a lot of the revealing data in the various occupation strata. But until he dug there, the Trojan War story had dwindled into a work of fiction in the minds of most scholars.
It isn't just Troy, either -- a French archaeologist excavated the Temple of Delphi over a century ago, and wrote that there was zero evidence of any kind that the ancient descriptions of the temple interior were correct. Then, late in the 20th century, a geologist invited in by the Greek gubmint mapped not one, but two fault lines, and they cross right under where the pythia sat and prophesied. Further research showed that there had been a gas seeping from the cracks in the floor that caused a "high".
One of the things that bothered Schliemann was the small size of his Troy, but the current modern dig at the site has uncovered the rest of the ancient city, spread out around the citadel. Schliemann didn't find it because he never looked for it. He was a pioneer, and a smart guy, an autodidact, but he had his faults as we all do. :^)
Schliemann was the first "modern" archeologist, on a hunt for proving that something ( in this case Troy ) had actually existed. Modern methods and techniques hadn't yet come about, so yes, he was a "BULL IN A CHINA SHOP", in his ham handed search. Still and all, he DID prove that there had been cities on that spot, wars and a great fire destroyed what was left of the buildings on that site, and the jewelry he decked his wife in, is an amazing find; though those jewels were probably from a later date than the sack of Troy, in The Iliad.