Complex sentence: When the Committee of Secret Correspondence sent Silas Deane (Bancroft's former teacher) to France in 1776, Franklin wrote Deane telling him to contact Bancroft, suggesting Franklin believed Bancroft would be a source of useful information for Deane.
Split into simpler sentences: When the Committee of Secret Correspondence sent Silas Deane (Bancroft's former teacher) to France in 1776, Franklin wrote Deane telling him to contact Bancroft. This suggests that Franklin believed that Bancroft would be a source of useful information for Deane.