David Rockefeller, the last surviving grandson of John D. Rockefeller, was laid to rest during the first week of April in Westchester, N.Y., after a private funeral. He was 101. His obituaries extolled his banking career, his global accomplishments and, of course, his wealth. Most likely the last high-profile member of one of America’s most fabled families, the former chairman and chief executive of Chase Manhattan bank exerted influence in the corridors of power around the world.

But David Rockefeller’s lasting legacy may well be more about philanthropy than his business and geopolitical exploits. He gave $1.8 billion to charity, according to Seitel, more than any of his brothers—John, Nelson, Winthrop or Laurance.

Some of that philanthropy, however, has fomented a family insurrection and led to a fierce and very public battle with ExxonMobil, the direct descendant of John D. Rockefeller’s Standard Oil Company. At the center of this skirmish are two family charities: the Rockefeller Family Fund, created in 1967 by David and his siblings to encourage their grandchildren to become involved in philanthropy, and the Rockefeller Brothers Fund, created in 1940 by David and his four brothers. The research and reporting financed by these two funds led to groundbreaking reports in 2015 that ExxonMobil knew decades ago, from its own research, of the causal connection between the consumption of fossil fuels and climate change.