THE FAMINE SHIPS: The Irish Exodus to America.<i> By Edward Laxton</i> .<i> Henry Holt: 250 pp., $27.50</i>

The Great Potato Famine of the mid-19th century is the defining event in modern Irish history. Between 1846 and 1853, an Irish population of about 9 million was reduced by more than 2 million. More than a million people died of starvation and disease, and another million immigrated to England, Canada, Australia and the United States. By the end of the century, with continued emigration and with an extraordinarily low post-famine birthrate, the total population was down to only 4 million, or about where it had been in the 1750s, and rural Ireland was virtually depopulated.

If anything, famine death rates are probably understated. Irish peasants were poorly adapted for emigration, and the average life expectancy of famine-era immigrants to America may have been as low as six years. Many never got farther than the dirt cellars of Liverpool and Glasgow, where they huddled and died by the tens of thousands. For a century or more, the Irish culture and national personality were stamped by the memory of Ireland’s own private holocaust. It intensified the ancient hatred for the English and is at the root of the legendary Irish sexual prudery. Aspiring Irish simply could not afford large families, or often any family at all. The average age of marriage rose sharply, and about 30% of Irish adults settled for lifelong spinsterhood or bachelorhood. By the end of the century, newly minted priests and nuns may have been the island’s most important export.

The 150th anniversary of the famine has been seized on as an occasion for reviving famine consciousness, and not only in Ireland. Our modern sensibility cherishes the remotest claim to victimhood, and several proposals have been floated in America for making the famine a mandatory part of high school history curricula. Edward Laxton’s “The Famine Ships” is an attractively packaged volume, designed to capitalize on heightened famine awareness.

The famine was not an unavoidable consequence of an unfortunate crop failure, for Ireland produced more than enough food to feed its population throughout the famine years. Irish agriculture had been commercializing ever since the Napoleonic wars, and the land was mostly owned by absentee British landlords, who supported their estates at home from Irish rack-rents. So Irish “strong farmers,” who ran the most modern farms, exported their crops and expanded wool production to pay their rents.

The peasants were squeezed onto increasingly marginal land and became almost totally dependent on the potato, which would grow almost anywhere. They were therefore utterly vulnerable when a blight--a fungus of American origin, Phytophthera infestans--struck their crops. The same blight devastated German potato crops in the 1850s, but suffering there was minimal because the rural population was not so dependent on a single food source.

Assigning blame, however, is tricky. There were no pogroms, gas chambers or mass executions in the desert, as in Armenia in 1915. It was a crime that took centuries to perpetrate. A vindictive English colonial administration, the anti-Catholic Penal Laws and a land policy aimed at breaking up economically viable Catholic holdings conspired to keep Ireland poor and dependent. Mini-famines were a regular occurrence by the 1830s, and Ireland was teetering on the brink of disaster well before the arrival of Phytophthera.

“The Famine Ships” concentrates on the flight of the peasantry once the famine struck. For all the complexities of assigning blame, the period produced more than its share of moral criminals. Among the most notorious were grandees like Lord Palmerston, a member of the British government and owner of vast tracts in Sligo in northwest Ireland. When Palmerston discovered that ship passage to America for his peasants cost less than the famine-era “poor rate,” a kind of welfare tax to support work houses and soup kitchens, he shipped all his peasants--young and old, the halt and the lame--off to Canada in mid-winter. These were the famous “coffin ships”--crowded, dirty, barely seaworthy, disease-ridden, with death rates 20 or more times higher than in normal times. The hapless peasants were often locked in the holds for voyages that stretched out to eight weeks or even more, surviving with minimum sanitation, short water rations and spoiled food, shrieking in terror as they were tossed in the dark during storms.

Laxton, however, seems unsure whether he is producing an undersized coffee table book or a light popular history, so he doesn’t quite succeed at either. He does not attempt to present a coherent picture of the famine emigrations or even of the passenger trade. Instead, after a very brief historical introduction, he strings together an interesting series of short vignettes about the individual voyages, the captains, the ships, the shipwrecks and the families, like that of William Ford, who survived the voyage, became a successful farmer and fathered the automobile tycoon.

A British newspaperman of Irish descent, Laxton writes serviceable, if occasionally stilted, prose. One of his best chapters, perhaps, is an account of the dreaded Grosse Isle quarantine station in the harbor outside Quebec. The worst year of the coffin ships was 1847. Emigration was increasing fast, and the British authorities were not yet enforcing minimum standards for hygiene and provisioning. Coffin ships arrived by the hundred, full of typhus--”ship’s fever” in those days, a deadly infection transmitted by body lice--and queued up for days, dumping their dead overboard as the fever raged.

Laxton’s volume is a useful and attractive introduction to one of the truly portentous events of modern history. Readers looking for the whole story of the famine, told with feeling and literary flair, will find that Cecil Woodham-Smith’s “The Great Hunger,” now 35 years old, is still unsurpassed.