White-throated Sparrows

I noticed that they were back for the first time yesterday and was very happy to see them. They looked like friendly companions hopping around under the feeders, scratching the ground together. But this morning I was startled out of my reading by the loud thud of one hitting the window. It was lying stunned on its back. One of its 'companions' came, jumped up on its stomach and began pecking wildly at its head from side to side. A few seconds later a third white-throated sparrow dive bombed them. For a split second all three of them were on their feet in a tight little circle, including the formerly stunned one. Then they all flew quickly into the woods. Now what was that little drama taking place right before my voyeuristic eyes all about? A love triangle maybe?