Falling Skies, Season 1 (2011)

When alien spaceships arrive at the Earth, human governments initially react with caution and restraint, in the hope the visitors may be friendly.

Six months later, those governments no longer exist, the the basic unfriendliness of the aliens has been well established for the rag tag "soldiers" of the 2nd Massachusetts, a resistance unit formed of all those willing to fight, be they trained military, former history teachers, or 13 year old boys.

Even after half a year, little is known of the enemy - six legged creatures the resistance calls "skitters" - or their agenda on Earth.  There are a number of strange elements to the alien's behaviour: why are their robotic troopers bipedal when they are not, for instance, and for what possible reason would they have human slaves gathering scrap iron? 

Of course for many members of the resistance, the "why" of the situation isn't that important.  They focus entirely on keeping themselves and the civilians they defend alive against threats both alien and human.  But of course for those in positions of authority the "why" is a nagging question, since to understand your enemy's motives will help you predict his plans ...

Falling Skies draws heavily on the American War of Independence, to the point of having its main character be a professor who specialised in the period.  Personally, I found his frequent speeches likening their struggle to various 18th century battles got a bit annoying, especially since they ignore some important differences between the two situations: British troops in the 1770s did not have quite the same technological edge that the aliens enjoy, for instance.  A better comparison might have been the Vietnam War, though of course that would have taken a lot of guts for them to do!

My occasional sighs over the "Ra-ra!  Freedom!" speeches aren't a major strike against the show, but there is another issue that I do think is worth mentioning, and that's a character who is introduced in the second episode.  He's clearly going to be a major player in the show, and we're just as clearly meant to find him to be this charming rogue.  The thing is, he's also (in the best case) turned a blind eye to his men committing rape.  So frankly, I hate him and I very much doubt the show will ever acknowledge his awfulness, let alone have him atone for it, so I fully expect to keep hating him for all five seasons.

If that character's not a deal breaker for you, this is an otherwise decent "alien invasion" TV series.