Two warring countries decided to settle the war finally in one specific week, and whoever would win that week would rule over the other. All week long they fought, one day one winning, and one day the other. Before the last day one country had an idea. They sent a special unit in the middle of the night to steal all the other country’s weapons. The next day the war was over quickly because only one country was armed.
So it is with the evil inclination, once we win and once he does. When time comes to an end, he decides to steal our most powerful weapon, Torah learning, as our Sages said, ‘I created the evil inclination, and I created the Torah to [protect you from it]’. Since the Torah is our strongest weapon, the evil inclination targets it for its last charge, and we have to hold on to it for dear life.