Sentence:  In that flickering pallor it had the effect of a large and clumsy black insect, an insect the size of an <WSD>ironclad</WSD> cruiser, crawling obliquely to the first line of trenches and firing shots out of portholes in its side. 
Meaning of the word marked with <WSD> tags:  Covered with iron, steel, or some metal, armor-plated.