Jennie Jerome was a pioneering "dollar princess," an American girl from an affluent Brooklyn family who married into the British aristocracy. Her husband Randolph Churchill had a short brilliant political career. She had two sons, one apparently surely by Randolph, Winston. Her second son, John, had Evelyn "Star" Boscawen for a father. Jennie helped Randolph's career and later helped her first son Winston's career. She died of a hemorrhage in 1921 so she did not witness his rise to Prime Minister. Winston, the result of an Anglo-American alliance, produced another from 1939 on with Franklin Delano Roosevelt. The alliance has had its ups and downs, especially in 1956 over Suez and 1963 over Skybolt, but it bore fruits for both in 1945, the UK in 1982 in the Falklands-Malvinas dispute, and the USA in 2003 when the UK helped Bush attack Iraq on dubious grounds. Another Winston Churchill contribution was his promoting the idea of a "landship" to break the deadly trench stalemate of World War I. American Caterpillar tractors for farms showed how to do it - just add armor and guns. The early ones were named "water tanks" to deceive enemy intelligence and they have been called "tanks" ever since.
Her Wikipedia article is here.