Which Legion was where?

Okay, so Gaius Trebonius had three legions at the siege of Massila in April 49BC...but which ones were they? An easy question? Well, not so fast. When Julius Caesar crossed the Rubicon during the evening of January 10th, 49BC, he had nine legions spread throughout the two Gallic provinces and was in the process of raising another three. Of these there were his four famous Spanish legions - the 7th, 8th, 9th and 10th, plus his newer Gallic Legions the 6th (the Italian Draft from 52BC), 11th, 12th, 13th and 14th. Being January, the legions were in their winter camps, the 7th, 10th, 12th & 14th were in the Rhone Valley city of Decetia under the command of the Senior Legate, Gaius Fabius. The 6th, 8th, 9th &11th were in the lands of the Belgic Remi at Andematunnum under the other Senior Legate, our Trebonius. Julius Caesar was in Ravenna, his Cisalpine Gaul base with just the 13th Legion. So when he crossed the Rubicon and invaded Italy he had just the 13th. Trebonius has sent the 8th legion through St Bernards Pass (in the middle of winter) but it was sixteen days behind, while Fabius had sent the 12th across the lower Alps. After subduing Northern Italy Caesar chased his conservative enemies to Brundisium with the 8th, 12th & 13th, plus his new recruits from Cisalpine Gaul and a few thousand Italian conscripts he'd shaped into the 16th, 17th and 18th Legions along the way. Okay, so who ended up at Massilia? Well, Trebonius headed south during January with the 6th, 9th and 11th to wait at Vienna in the southern Rhone Valley to see if Caesar would need more help in Italy or if  Fabius - who was moving towards the Spanish border with the 7th, 10th and 14th - ran into Pompey's Spanish Legions. At this stage Massilia wasn't an issue. Things only changed when the Caesar was taking the 12th, 13th and 18th from Italy back across Gaul to join Fabius and Trebonius for a war on Spain in April. He more or less came across Massilia in the hands of the enemy during what he intended to be peace negotiations. Luckily for him he hand three legions with him (the 12th, 13th and 18th) but he wanted to go to Spain and have someone else take command of a simple urban siege...and since it was easier to transfer a Senior Legate than an army, he brought Trebonius over to Massilia. So which legions were at Massilia? Drum roll for those who've managed to stay with me this far.

It was the veteran Gallic legions the 12th & 13th plus the newbie Italio/Gallic 18th Legion.

Find out if Calvus has any idea what I just said