Instructions: This task involves annotating the answer type to a given question that involve some kind of complex reasoning (including numerical reasoning). Note that the questions require looking at more than one part of the passage to answer. There are 3 possible answer types (i) spans, (ii) numbers and (iii) dates. If the answer can be found in the passage, label it as "span". If the answer is a number, label as "number". Similarly, label "date" if you think the answer to the given question is a date.
Input: Passage: In November 1656, De Bitter was made Vice-Commandeur, under Commandeur Adriaan Roothaas, of a fleet sent to blockade the Portuguese ports on the coast of Malabar. In the spring of 1657 he returned to Batavia; in August that year he again served under Roothaas on a flotilla blockading Goa. De Bitter's flagship Terschelling captured the Santa Cruz loaded with spices. De Bitter embezzled some of the cargo, for which he would later be lightly punished. The flotilla having been joined by the main force of Colonel Rijcklof van Goens in November, it was decided to split off a large part of the fleet to attack the remaining Portuguese possessions on Ceylon. De Bitter was also used for this expedition, now commanding a larger ship, the Salamander. This ship and the Naarden had the mission to mislead the Portuguese by first sailing to the north and only afterwards rejoin the main force leaving for Ceylon. This ruse failed, however, because adverse winds drove the vessels towards the Maldives. De Bitter only reached Colombo on 17 February 1658, too late to contribute to the capture of Manaar. However he participated in the fall of Jaffnapatnam on 21 June. Again he was used as a messenger to the Council. On 19July 1659, De Bitter, still serving under Roothaas, departed on a fleet of thirteen headed for Goa, on the yacht Tholen. Blockading the port De Bitter confiscated an English vessel, the Constantinople Merchant, on accusations of carrying contraband.
Question: When did De Bitter first serve under Roothaas?
Output:
date