Split infinitives occur when additional words are included between to and the verb in an infinitive. Many readers find a single adverb splitting the infinitive to be acceptable, but this practice should be avoided in formal writing.
When he was 11 years old, Itachi was also under orders from his father to enroll in the Anbu half a year later. Itachi was praised highly by Fugaku, who spent most of his time grooming Itachi to inherit the title of leader of the Uchiha, and hence inadvertently neglected his younger son.
After Itachi dies in battle with Sasuke, however, Sasuke learns that the hateful older brother that Itachi seemed to be was an act and that, in truth, Sasuke was the most precious person to Itachi; his murder of the Uchiha was done on instructions of Konoha, in order to protect Sasuke.