Sentence:  The first occasion that the <WSD>Tallboy</WSD> was used in support of the Normandy campaign was on the night 8-9 June against the Saumur railway tunnel....Twenty three <WSD>Tallboys</WSD> were dropped, most falling near the markers at the mouth of the tunnel causing great damage. 
Meaning of the word marked with <WSD> tags:  An (earthquake bomb) developed for the (British Armed Forces) and deployed by the RAF during World War II.