example of Roman loss in battle was the Battle of the Teutoburg Forest in AD 9, where three entire legions led by Publius Quinctilius Varus were destroyed by Arminius, leader of the Cherusci, an apparent Roman ally. Augustus retaliated by dispatching Tiberius and Drusus to the Rhineland to pacify it, which had some success although the battle brought the end to Roman expansion into Germany. Roman general Germanicus took advantage of a Cherusci civil war between Arminius and Segestes; at the Battle of Idistaviso in AD 16, they defeated Arminius. Death and succession The illness of Augustus in 23 BC brought the problem of succession to the forefront of political issues and the public. To ensure stability, he needed to designate an heir to his unique position in Roman society and government. This was to be achieved in small, undramatic and incremental ways that did not stir senatorial fears of monarchy. If someone was to succeed to Augustus's unofficial position of power, he would have to earn it through his own publicly proven merits. Some Augustan historians argue that indications pointed toward his sister's son Marcellus, who had been quickly married to Augustus's daughter Julia the Elder. Other historians dispute this since Augustus's will was read aloud to the Senate while he was seriously ill in 23 BC, indicating a preference for Marcus Agrippa, who was Augustus's second in charge and arguably the only one of his associates who could have controlled the legions and held the empire together. After the death of Marcellus in 23 BC, Augustus married his daughter to Agrippa. This union produced five children, three sons and two daughters: Gaius Caesar, Lucius Caesar, Vipsania Julia, Agrippina, and Agrippa Postumus, so named because he was born after Marcus Agrippa died. Shortly after the second settlement, Agrippa was granted a five-year term of administering the eastern half of the empire with the imperium of a proconsul and the same tribunicia potestas granted to Augustus (although not trumping Augustus's authority), his seat of governance stationed at Samos in the eastern Aegean. This granting of power showed Augustus's favor for Agrippa, but it was also a measure to please members of his Caesarian party by allowing one of their members to share a considerable amount of power with him. Augustus's intent became apparent to make Gaius and Lucius Caesar his heirs when he adopted them as his own children. He