Task: Question Answering
Input (English): Passage: As enthusiasm for war rose among the English populace, privateers began to attack Dutch ships, capturing them and taking them to English harbors.  By the time that Charles II of England declared war on the United Provinces about two hundred Dutch ships had been brought to English ports.  Dutch ships were obligated by the new treaty to salute the English flag first.  In 1664, English ships began to provoke the Dutch by not saluting in return.  Though ordered by the Dutch government to continue saluting first, many Dutch commanders could not bear the insult. Still, the resulting flag incidents were not the casus belli as in the previous war. To provoke open conflict, James already in late 1663 had sent Robert Holmes, in service of the Royal African Company, to capture Dutch trading posts and colonies in West Africa.:67  At the same time, the English invaded the Dutch colony of New Netherland in North America on 24 June 1664, and had control of it by October. The Dutch responded by sending a fleet under Michiel de Ruyter that recaptured their African trade posts, captured most English trade stations there and then crossed the Atlantic for a punitive expedition against the English in America.:68 In December 1664, the English suddenly attacked the Dutch Smyrna fleet.  Though the attack failed, the Dutch in January 1665 allowed their ships to open fire on English warships in the colonies when threatened. Charles used this as a pretext to declare war on the Netherlands on 4 March 1665. 
Question: How many months after the English invaded the Dutch colony of New Netherland did the English attack the Dutch Smyrna fleet? 
Answer type: Number 
Output (English): 6.