No doubt a good number of Jews have been subversive, or in many cases a non-factor either way, but for the sake of edification this will be an attempt to highlight some of the cases where Jews have been of benefit.

From Leon's The Jewish Question:

http://www.marxists.de/religion/leon/ch3b.htm

The financial support furnished the kings by the Jews was indispensable to them in their struggle against the nobility as well as in their opposition to the growing demands of the cities. It was the Jews who first permitted the kings to maintain costly armies of mercenaries which begin to take the place of the undisciplined hordes of the nobility These armies first served foreign policy. Thus, in Spain, it was in large part Jewish finance which allowed the kings to defeat the Arabs. “In 1263, the Jewish banker Jehudah de Cavallera loans the king [of Aragon] a great sum which permits him to equip a flotilla against the Arabs. In 1276, Cavallera amasses funds for an army which fights the Arabs at Valencia.”

https://en.wikipedia.org/wiki/Samuel_Oppenheimer

Samuel Oppenheimer (born June 21, 1630, Heidelberg – May 3, 1703, Vienna) was a Jewish banker, imperial court diplomat, factor, and military supplier for the Holy Roman Emperor. He enjoyed special favor of Emperor Leopold I, to whom he advanced considerable sums of money for the Great Turkish War.

The Great Turkish War, as some may know, included the Battle of Vienna (1683).

http://www.heymannfamily.com/other%20families/Oppenheimer/Samuel%20OPPENHEIMER%20Court%20Jew%201630%20-1703%20HR.jpg

The House of Rothschild:

https://en.wikipedia.org/wiki/Rothschild_family

The Rothschilds financed the founding of De Beers, as well as Cecil Rhodes on his expeditions in Africa and the creation of the colony of Rhodesia.

The Rothschilds, Disraeli, and the acquisition of the Suez Canal:

https://en.wikipedia.org/wiki/Benjamin_Disraeli

Disraeli was, according to some interpretations, a supporter of the expansion and preservation of the British Empire in the Middle East and Central Asia. In spite of the objections of his own cabinet and without Parliament's consent, he obtained a short-term loan from Lionel de Rothschild in order to purchase 44% of the shares of the Suez Canal Company.

Disraeli is one of my favorite British leaders.

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQhVz7rEX6S4qHsyKgA9QPVGLI1T26rRR5kzNEWS_Mp8RN9f7Y9

And...

https://en.wikipedia.org/wiki/Luis_de_Sant%C3%A1ngel

Luis de Santángel (or Santander) (died 1498) was a baptized Jew and finance minister to Ferdinand II who made the case to Isabella I in favor of Christopher Columbus' voyage in 1492.

https://upload.wikimedia.org/wikipedia/commons/f/fb/Luis_de_Santangel.jpg