Sentence:  Many a seaman's life may have depended on equine speed and strength. Some of these ‘Lifeboat Horses' used to recognise the <WSD>maroon</WSD> which was fired to summon the Lifeboat crew. Long after its retirement one of the horses which regularly helped to haul the Hoylake Lifeboat heard a <WSD>maroon</WSD> fired one day when it was working in the neighbouring fields. It immediately became very excited and made for the boathouse. 
Meaning of the word marked with <WSD> tags:  A rocket-propelled firework or skyrocket, often one used as a signal (e.g. to summon the crew of a lifeboat or warn of an air raid).