This intriguing and often-repeated rumour is partly true. The sultan did donate a large sum of money, £2,000, to Ireland, but there is no evidence that he also sent food aid in the form of three ships laden with produce, which (in some tellings of the tale) had to sneak past a Royal Navy blockade to land their cargoes.

I investigated the story in some depth a few years ago, and wrote up the results for my website. Since the essay exactly addresses your question, I am copying it here. Hope it helps!

Queen Victoria’s £5: the strange tale of Turkish aid to Ireland during the Great Famine

The most striking thing about the ghastly blight that ruined Ireland’s potato crop in 1845 was that the harvest had seemed healthy, even robust, when it was lifted from the ground.

Within a day or two, however, rot set in. Potatoes that had looked firm and edible turned black and then disintegrated into a stinking, liquid mess. No one knew why. John Lindley, the editor of the Gardeners’ Chronicle, guessed that this “wet putrefaction” was a disease borne in from the Atlantic by torrential gales. Others thought that the blight had somehow risen up from underground, so that the soil itself was now infected.

The one certainty was that every measure tried to save the harvest failed. “All specifics, all nostrums were useless,” the historian Cecil Woodham-Smith observed. “Whether ventilated, desiccated, salted, or gassed, the potatoes melted… and pits, on being opened, were found to be filled with diseased potatoes–‘six months’ provisions a mass of rottenness.’” The blight struck everywhere that year, from North America to Belgium, and the Irish had long been distressingly familiar with disastrous harvests; twenty-four previous crop failures had been recorded between 1728 and 1844. Several of these had caused suffering “horrible beyond description,” and it has been estimated that very nearly half a million people died during Ireland’s “Year of Slaughter” (1740-41), when a freezing winter caused the oat crop to fail. But the catastrophe of 1845 was was remembered as the greatest of them all, and it affected Ireland more profoundly than it did anywhere else, with the possible exception of the Scottish Highlands.

The underlying reason why the famine’s impact was profound was that the Irish population had ballooned at the same time as the amount of land available for Irish tenants to farm had been falling sharply. Ireland’s population rose from 3.2 million in 1750 to 8.2 million a century later: an enormous total, nearly a third higher than it is today. As it did so, the enclosure and seizure of what had once been common land by wealthy Protestant landowners was significantly reducing the acreage available to Catholic peasant farmers. The result was a severe shortage of land. By 1845, at least a quarter of Irish families scratched a living from tiny plots of five acres or less, and this in turn meant that, in order to survive, families had to turn over all their land to the cultivation of the highest-yielding, most nutritious crop. By 1845, the potato was not only the staple, but in many cases the only, food sustaining a huge number of men, women and children.

The blight (which we now know was caused by a fungus) thus brought with it five long years of starvation. While the disease reigned, perhaps a million died of hunger in Ireland, and 1.5 million more were forced to emigrate. Had overpopulation been the sole cause of the catastrophe, the Great Famine of 1845-51 would be remembered today as a natural disaster on a grand scale – an act of god that could not have been averted. But the Ireland of the 1840s was a country run largely for the benefit of its landowning class. It was also scarcely some remote community on the fringes of the world, forced to fall back on its own inadequate resources. It lay close to the heart of the British empire, which was then the richest and most powerful state on earth. Had the British really wanted to, they could have harnessed those resources and minimised the loss of life. They failed to do so, and, in consequence, the famine produced bitter resentment in Ireland at the time – and a rich folklore thereafter.

Two tales in particular emerged from all this anguish and anger, and are still widely believed in Ireland today. Both involve immensely wealthy monarchs – the first Queen Victoria and the second Sultan Abdülmecid (Abdul Mejid) I, who ruled the Ottoman empire from far-off Istanbul. Both accounts deal with the ways in which powerful rulers responded to the misery in Ireland. But while Victoria’s actions were found wanting, the story of Abdülmecid’s munificence was held to shame the Queen, and it became such an article of faith that it was immortalised in Ulysses. “Even the Grand Turk sent us his piastres,” one of Joyce’s characters explodes in the midst of a harangue against the British. “But the Sassenach [Englishman] tried to starve the nation at home while the land was full of crops that the hyenas bought and sold in Rio de Janiero.”

The details of the two legends are straightforward, though their origins are a good deal less so. Ireland’s hatred of Victoria is rooted in the firm belief that the British queen contributed a paltry £5 to the cause of famine relief – that at a time when desperately poor Irish emigrants, struggling to survive in the slums of New York, contrived to send home more than $326,000 [about £9 million today] in just two months, and even the Choctaw tribe, ravaged by disease and confined to a reservation in far-off Oklahoma, donated $710. Victoria’s contemptuous act of indifference appears in a variety of guises; the Irish nationalist leader Charles Parnell once delivered a speech asserting that she gave absolutely nothing. The most damaging version of the tale, however, adds that, on the same day that the queen made her pathetic donation, she gave a considerably larger sum to an English dogs’ home. That incendiary suggestion certainly helps to explain how Victoria acquired the nickname of “the famine queen,” by which she is still commonly known in Ireland – not to mention why (as one historian notes), when a crowd gathered to watch her statue being removed from its plinth some years after the country attained independence, somebody “stepped forward and waved a five pound note in the face of the bronze monument…. [and] everyone realised the significance of the gesture.”

What Sultan Abdülmecid did, meanwhile, is just as difficult to make out. It is generally accepted that the sultan sent a personal donation of £1,000 to London – an act of considerable generosity, particularly when it is remembered that there were no links of any real significance between Ireland and Turkey. But some accounts suggest that he did much more than that. In one version of the story, the sultan tried to give as much as £10,000 [£1 million now], only to be told that it would be diplomatically embarrassing for him to donate significantly more than had Victoria. In another, he responded by reducing his gift to a more acceptable amount – while simultaneously making sure that further help was sent behind British backs. It is still quite commonly believed in parts of Ireland that this aid took the form of several Turkish ships, which were quietly sent to unload badly needed foodstuffs in a port on the east coast. One telling of the tale even suggests that Abdülmecid’s merchantmen had to run the gauntlet of a Royal Navy blockade in order to bring their life-saving cargoes in Ireland.