I've done away with fence stretchers and splices...I use one real good fencing plier/hammer and one claw hammer (mainly for leverage)...then I run a piece of #9 wire between the broken barbed wire pieces...loop the left side with the #9 wire (looped on that end also)...then on the right side of the #9 wire, loop the barbed wire and run the #9 thru it (UP through it, not facing down).... (it's important to work left to right).
then you feed the #9 wire through the fencing plier and get a grip on it, then put your hammer thru the handles of the pliers (like a T), then roll the #9 wire to the RIGHT until you get it as tight as you want it (I know, it sounds backward to roll right, but it's not, trust me)....then you loop the #9 wire as usual to the barbed wire and your fence will not give when it's released.
It's much easier to demonstrate in person, but it is a great way to fix fence and a heck of a lot easier to carry the supplies on horse back versus stretchers.....just precut your #9 wire to the length you want and off you go.
A guy that all he did was fix fence on a huge ranch in New Mexico taught this way of fixing and he's right on in how to do it...once you catch on to it, it saves lots and lots of time in doing it from the standard method!! #9 wire is awful strong too, I haven't had a fix like that break yet.
hope i've made it clear on how to do this method...it really is a time saver 8)