From notes and books and articles: On Agrippa aes issues
Mattingly recognized this issue being assigned to Caligula in BMCRE1 pg. cxxxiii
Michael Grant in NC, 8 (1948) pg 125-26
Sutherland- CRIP 102
Sutherland wrote: "Whose abundant frequency has long made them a puzzle to interpret , were more probably struck under Gaius, to judge from the dates of other coinages which reproduce the designs'/, although he has regarded it as just possible that they came out at the very end of Tiberius' principate, CRIP 102 no.2) After Anne Robertson wrote. (Roman Imperial Coins in the Hunter Coin Cabinet 1 (1962) pg. lxv, added a technical argument in favor of the coins being struck under Gaius. The fact that the obverse and reverse types on these coins are regularly at 180 in relation to one another, for this did not become the regular die arrangement for aes coinage prior to Gaius reign. It was usual in the middle years of Tiberius' reign, but not dominant. These arguments have convinced Macdowall NC7 (1967) 47, no.5 that the majority of these aes issues must have been Caligulan, while Giard believes the attribution of the whole issue belongs to Caligula is, at present, the most probable hypothytheis, on grounds of community both of style and of countermarks. (Rev Num. 10 v.6 (1968 ) 80-81.
However, Sydenham has already urged (NC 17) 1917 that Caligula's reign was too short for so vast an issue, and after the publication of Sutherlands book Carl Kuthmann argued afresh in favor of attributing the whole issue to the reign of Tiberius, other aes issues being, in his view, ample in number and size to fill Caligula's reign. (Schweizer Munsblatter 4 1954 73-7. He suggested that the coins of Caesaraugusta in Spain which Sutherland gave as his example of coins reproducing the design of Agrippa asses were probably struck, not under Caligula, as Sutherland held, but under Tiberius. In A.D. 37, and that the appearance of countermarks from Claudius' reign on some of the Agrippa asses (Kray Vindonissa 48) Is not at all suprising , the reign of Caligula being so short. He also suggested that the reign of Tiberius is the most likely historical context for this advertising of Agrippa , since there was a strong personal tie, through Vipsania, between Agrippa and Tiberius (CE Stevens has quoted Velleius 2. 127) For Agrippa's high standing A.D. 30 (NC 7 . 3 (1963) p.262. But the fact that Caligula was Agrippa's grandson, none between Agrippa and Caligula (Suetonius Gaius 23) Mattingly has said in conversations, " that he still holds these historic considerations as weightier than the numismatic arguments against inception under Tiberius. He believes that the bulk , at least, of this issue was produced between 22- 31 A.D. Note 576. While Sejanus was influential , unfortunatley the political question , cui bono? Who is most likely to have wanted to advertise Agrippa? Above all to the troops on the Rhine and Danube frontiers , and at what period? cannot be given an answer that will convince everyone, as is shown in the diversity of views about personal relationships at this period. See: (Anne Boddington AJP 84 1963 1-16) S. Jameson, however, has argued, on the evidence of the die axis and of hybrids that occur, that one of these 3 groups into which she believes the issue can be divided began began to be produced in about 22-23 A.D. ; minting "will have covered a span of several years". (NC 7. 7 (1967) 95-124. But prof. Robertson draws a different conclusion from the die-axis and John Nicols (ANS Museum notes 19 1974) has shown the flimsiness of the hybrid evidence, the fact that 18 halves of asses of the other great issue, celebrating the providentia of Augustus , were found at Vindonissa , but no halves of these asses is, as he says, "fairly strong evidence against assigning a mid-Tiberian date to the Agrippa as.
Grant States: If one weighs up the historical and numismatic arguments, no one of which is desicive, it seems most likely that the production of these asses began in the later years of Tiberius' reign, already with the intention , with the intention, at least that the issue would be large. However, C.M Kraay while believing that the major part of it, including all the coins struck at Rome, belongs to Tiberius' last years , has pointed to find evidence indicating that in Gaul some production ran much longer. (Vindonissa 10 35)