Complex sentence: Even though the letters of recomendation written for him by those under whom he had studied showed that he was held in high esteem by those at Cambridge, he failed to get the appointment and decided to try for a fellowship in Trinity College.
Split into simpler sentences: Even though the letters of recomendation written for him by those under whom he had studied showed that he was held in high esteem by those at Cambridge. Yet, he failed to get the appointment and decided to try for a fellowship in Trinity College.