The year 1788 witnessed the first steps taken in Parliament for the abolition of the slave trade. Wilberforce a prominent leader in the movement succeeded in winning over Pitt to the cause, and the City threw its influence into the scale. On the 4th February, the Common Council petitioned the House to take the matter into its consideration.[539] Little however was done beyond the introduction of a temporary measure for improving the sanitary condition of vessels employed in the slave traffic. The Bill passed the Commons, but underwent such a change in the House of Lords that it became practically useless. In 1789, and again in 1790, Wilberforce urged the Commons to abolish the slave trade in its entirety, and in 1792, Pitt supported the proposal in a speech which surpassed all his previous oratorical efforts. It was to no purpose. The Liverpool merchants, whose interests in the nefarious traffic were enormous, succeeded in frustrating every attempt to put it down. At last, even the city of London refused to petition Parliament any further on the matter.[540] [Sidenote: Pitt's Regency Bill, 1788-1789.] In the meanwhile an event had occurred which for the moment threatened to overthrow the ministry. In November, 1788, the king who had previously shown signs of mental derangement became so seriously ill that a regency seemed inevitable. That the Prince of Wales ought to be Regent all parties were agreed, but whether he should be allowed to take upon himself the regency as a matter of right, or whether he should accept it at the hands of Parliament and with such limitations as Parliament might think fit to create, opinions differed. Pitt was strongly in favour of upholding the authority of Parliament in the matter and introduced a Regency Bill. The Bill passed the Commons, but before it passed the Lords the king unexpectedly recovered, and further proceedings were stayed. For having thus maintained "the important right of the Lords and Commons of this realm to provide the means for supplying the defect of the personal exercise of the royal authority arising from his majesty's indisposition," the Common Council passed a vote of thanks to Pitt and his supporters, which the minister duly acknowledged;[541] but when it was proposed to present an address to the prince condoling with him on the king's illness, and congratulating him upon his being invested with the government "by the united wisdom of the two Houses," a debate of three hours ensued and the motion was eventually lost.[542] [Sidenote: Gift of £1,000 by Prince of Wales for poor of city, Jan., 1789.]