Just joined up on this board in order to catch up on all things Traveller after a long hiatus, and found this thread which I thought was a bit coincidental considering that last weekend me and several others in my gaming group had just finished up playing several games of Imperium. I had played the game many times back in the 80's as had one other player, but the rest were all new to the game. All of us however had quite a bit of fun with this gem despite a couple of rule concept fuzziness initially; mainly on the difference between connected outposts and sustainable outposts.
<Edit: I had originally written here that I had never heard, nor was it in the rules, that maintenance was skipped on the first turn...I was quite wrong>
Turns out, I've been playing Imperium wrong for a long time, as I suspect many others have as well in regards to maintenance, specifically first turn maintenance. As it turns out, after a bit of research, I found that Marc Miller did write up an addendum on Imperium in Dragon Magazine #20. In it he discusses maintenance and how it needs to be performed on ships loaned to the Imperial Governer by the Emperor, and that such ships when they leave must be fully maintained, and also that since new ships first appear in the movement phase after the maintenance phase, that maintenance does not need to be paid for them. At this point there is an asterisk in the article with an Editor's Note, the editor at the time being Tim Kask. Apparently he had run an Imperium tournament recently and made the following comment:
'Ed. Note: For my tournament, I asked Marc about Turn I, maintenance, as it has a distinct effect on the opening game. It was ruled then that maintenance need not be performed on Turn 1 as [
sic] starting forces.'
So there we have it, from Marc Miller himself. I believe the 'as' at the end of the line should have been 'on'. In any case, the intent is clear, no maintenance required for the first turn of the war. I believe that this would also apply to the first turn of each war in a campaign as well, the maintenance being rolled into the whole Interwar Attrition Phase during peace.
I have to say as well that I have seen no place in the rules where it is stated that there is a limit on the number of Planetary Defense markers that may be placed on or operated from one world or outpost, nor is it mentioned at all in the above listed Dragon article. So really, I don't see why the Terran couldn't just place both of the initial Planetary Defenses on Barnard's Star along with all of their other ground forces at start if they want to. Yes, it can indeed make such a system a rather tough nut to crack, especially with the limited forces available at the beginning of the game, but then again, each one costs 10 RU's and can very easily end up attritioned away during any extended peacetime. However in the later games of a campaign, when there are larger fleets and lots of Jump Troops and Regulars that can be committed to a planetary assault, you'll want to have that extra defense for a critical world if you can afford it.
And by the way, that idea of placing the Terran monitor on the surface of the planet in the first game is brilliant.
Anyway, as with all plans though, the best ones rarely survive contact with the enemy.

A couple of examples from two different Imperium games played last weekend. In the first one, being played by two new players to the game, the first player decided to not be a proper sensible Terran player, and so she took her entire force, transports and all, and attacked the Imperial stack at Aggida! Insanity! Well...turns out that day Lady Luck liked the Terrans (as you will see again later in the next paragraph...). Not only did she succeed on the first round of combat to destroy the Imperial Monitor with high intensity fire from her Missile Boat (a 50-50 proposition), she even scored a few hits on some Imperial Transports and a Scout I believe. Her losses consisted of the Missile Boat, a few Transports, and a Scout. Continuing her luck, helped by having the fewer units at the battle after the first round, she was able to gain the initiative and move the combat to short range. To make a long story short, the Imperial player got smashed, and despite a fair number of losses of her own, she then proceeded to have the advantage for the rest of the war. Risky to be sure, sort of a one battle risk it all thing for the Terrans.
In another game, a different Terran player defended Barnard's with 1 Monitor and 1 Scout. I believe he thought for some reason that the Monitor wouldn't stop Imperial starships from moving through the system. Anyway, the Imperial player reacted into the system in great force...and then proceeded to miss the Monitor with every missile he fired at it, including the expected two high-intensity attacks by the Light Cruisers. The range then proceeded to move to Short range, and the stodgy old Monitor proceeded to pick off little ships one by one as the range stubbornly stayed at short range for several rounds. Finally the range went back to long! At last! And...he missed his missile fire against the Monitor again. Not surprising really, 1 in 6 from the Heavy Cruiser is hard to come by when you really need it. The Monitor was smiling behind that 8 screen defense. Then, back to short range again for a few more turns, and a few more ships got picked off by the Monitor. When the range returned to Long again, the Imperial Player now getting desperate to get rid of this obnoxious Monitor tried high-intensity fire with his Heavy Cruiser...and of course, missed again. Well, so much for being able to take out the thing. He had to withdraw the next round having no other ships left with the combat strength to take out the Monitor, and he didn't dare try sending the Heavy Cruiser on a Suicide Run against it at short range; not the way his luck had been going! It really did ruin the Imperial war plans for that game. In the end, it really was pretty funny. Afterwards, the Terran player wanted to mark the counter with a little star to show that they had an elite crew. To which the Imperial player said fine, that way it would be easier to know which counter to throw into the fire.

Personally, I thought it was a great example of target fixation.
The two games also illustrated another point. Just how much of a difference that 1 point of defense has between the Imperial and the Terran Monitor. We saw that a mere 4RU Missile Boat could get a one-shot 50% chance to take out the Imperial Monitor, while the 12RU Heavy Cruiser could only muster a 33% chance under the same circumstances. Anyway, still a fun game after all these years, and I look forward to reading more on the OP's game.