Joe Sacco’s gripping, important book about two long-forgotten mass killings of Palestinians in Gaza stands out as one of the few contemporary works on the Israeli-Palestinian struggle likely to outlive the era in which they were written.

Sacco will find readers for “Footnotes in Gaza” far into the future because of the unique format and style of his comic-book narrative. He stands alone as a reporter-cartoonist because his ability to tell a story through his art is combined with investigative reporting of the highest quality.

His subject in this case is two massacres that happened more than half a century ago, stirred up little international attention and were forgotten outside the immediate circle of the victims. The killings took place during the Suez crisis of 1956, when the Israeli Army swept into the Gaza Strip, the great majority of whose inhabitants were Palestinian refugees. According to figures from the United Nations, 275 Palestinians were killed in the town of Khan Younis at the southern end of the strip on Nov. 3, and 111 died in Rafah, a few miles away on the Egyptian border, during a Nov. 12 operation by Israeli troops. Israel insisted that the Palestinians were killed when Israeli forces were still facing armed resistance. The Palestinians said all resistance had ceased by then.

Sacco makes the excellent point that such episodes are among the true building blocks of history. In this case, accounts of what happened were slow to seep out and were overshadowed by fresh developments in the Suez crisis. Sacco, whose reputation as a reporter-cartoonist was established with “Palestine” and “Safe Area Gorazde,” has rescued them from obscurity because they are “like innumerable historical tragedies over the ages that barely rate footnote status in the broad sweep of history — even though . . . they often contain the seeds of the grief and anger that shape present-day events.”