Depening on the game difficulty your player level and skill, you may need alot more men than 160, unless they are all danish elites / svear warriors or equivalent and your a level 50 berserkr called Rollo.
After Ascendun you are usually rewarded with 2 castles in the east angle area, these castles will have a garrison of over 100 men each, take those and with the additional 50 men you get before you attack the hideout you should have at least a chance.If you play on normal settings, you may need more men, as sven can field over 200 vikings, including 80 danish elites, that means you need >300 men.
Now it depends on your difficulty setting and player skill. When the battle starts there is not enough time to arrange troops, especially since sven attacks from the rear, the savest option is to order a full charge immidiately, most of your men will focus on the rear, you have to get behind those guys and attack from the rear and kill as many danish elites as possible. Depending on the player skill and level of the character you should be able to kill at least 50 men turning the tide in your favor. When you see that your men have the upper hand rush to the front and repeat. There it will be more difficult as you will get attacked so you cannot dish out as much but have to be more careful picking targets preferably stay on the flank and decimate them so your men can flank as well increasing the damage output.
Be careful once you won the battle outside, as there will be more to do inside, dont die.