Inter­est in the Revi­sion­ist Zion­ist Move­ment increased after the elec­tion of Men­achem Begin as Israel’s prime min­is­ter in 1977. The founder of the move­ment, Vladimir Jabotin­sky, is well known, but his assis­tant, Solomon (Sioma) Jaco­bi is not. The two exchanged over five hun­dred let­ters between 1920 and 1939. Rod­ney Ben­jamin, Jacobi’s son-in-law, and his grand­son, David Cebon, have reme­died this sit­u­a­tion with a biog­ra­phy based on those let­ters. Jaco­bi was born in Berdichev, Ukraine in 1897. He lived in Odessa and attend­ed the uni­ver­si­ty in St. Peters­burg, study­ing engi­neer­ing. Pogroms and the 1917 rev­o­lu­tion made life dif­fi­cult, so he found­ed the Jew­ish Defense Corps to pro­tect Odessa’s Jews. He went to Pales­tine in 1919 and met Jabotin­sky, who shared his views of Zion­ism and the need for a strong Jew­ish self-defense. Jaco­bi went to Eng­land to com­plete his stud­ies. He ran the Lon­don Revi­sion­ist bureau from 1934 until his death at the age of forty-two in 1939. The let­ters pro­vide a glimpse into the busy life of this ded­i­cat­ed activist. He trav­eled the world on behalf of the Zion­ist move­ment, vis­it­ing Jew­ish com­mu­ni­ties in Chi­na, Aus­tralia, and South Africa. He also dealt with the polit­i­cal splits in the move­ment and par­tic­i­pat­ed in the ille­gal immi­gra­tion runs dur­ing the British Man­date. This work is a wel­come intro­duc­tion to a leader who deserves more recognition.