Sichon and Og
I was unable to write something long, so a quick idea based on the Sfas Emes.
We constantly praise HaShem for our conquest of Sichon and Og. Every Shabbos morning (if we are on time and do not skip it J ) we say that HaShem’s Chesed is forever because we conquered Sichon and Og. What is so special about them?
Sichon is the king of Chesbon- calculation. Og is the king of Edrei, which means an arm. Everything in Kedusha has a counterpart in Tumah. Sichon is the anti of the Tefilin shel Rosh. All kinds of calculations of anti-Torah. Og is the force of the hand to be used against HaShem. The battles to enter Eretz Yisroel were to be able to fulfill the Mitzvoth completely. Sichon and Og would try to keep us from using there powers correctly. The destruction of them is each of our ongoing battle to overcome these forces counter to Torah.
On sShabbat, we do not wear Tefilin. But we mention these battles to remind us that on Shabbat, the day itself is to overcome these powers, and sue them correctly.