1:
The Hebrew word which I have rendered 'squad' could refer either to soldiers or to police, but since in the Roman empire there was no division between civil and military arms the difference is immaterial regarding our present discussion.
2:
Our mishnah presents a situation which no doubt reflects the realities of life in Eretz-Israel in Talmudic times. Armed men were likely to 'invade' a town on official business. They may be on their way to war; they may be on their way back from war; they may be searching for wanted criminals - whatever the purpose of their arrival it raises problems. One of the problems will be billeting - housing armed men in private homes. Another problem will be lawlessness: it is very difficult to maintain discipline among men who are armed and temporarily without subordination. In Talmudic times such men tended to think that they were entitled to whatever they desired - food, drink, women and so forth.
3:
Our mishnah states that if an armed squad arrives in a town the Jews face a problem with regards to wine. After the men depart any casks of wine that are open must be viewed as yeyn nesekh because it is most likely that the armed men helped themselves to wine. However, if there is a cask which is still closed it is permitted: since the seal has not been tampered with there is no reason to assume that the wine inside has become yeyn nesekh.
4:
However, if the squad has entered town in time of war the ruling is that regardless of whether the casks were open or closed they need not be considered to be yeyn nesekh. Our mishnah gives a reason for this ruling and it is important that we give this reason our consideration.
5:
Our mishnah says that in time of war, when there are active hostilities, the soldiers are far too busy to carouse. But more importantly, for our discussion, even if they do help themselves to some wine from an open cask or bottle they are in such a hurry that "they have no time to offer a libation." If no libation has been offered to the gods the wine cannot be considered yeyn nesekh. Instead, it is stam yeynam - wine handled by a non-Jew. You will recall that it is forbidden to derive any kind of benefit from yeyn nesekh: the loss for the Jew is complete. However, in the case of stam yeynam it would appear that in mishnaïc times the Jew suffered no loss. If a non-Jew touched or even drank Jewish wine without offering a libation to his gods it was considered to be stam yeynam. However, the sages in the Gemara took a more stringent view of stam yeynam. Their reasoning was that if Jews are permitted to carouse with non-Jews where will the matter end? It could lead to intermarriage; it could lead to apostasy! Therefore, the sages of the Gemara forbade a Jew from deriving any benefit from stam yeynam except the right to sell it and thus recover his loss.
6:
It now becomes clear that what constitutes yeyn nesekh is the fact that some of the wine was offered as a libation to the gods. It was a prevalent custom among non-Jews not to drink all the wine that was in their cup but to spill out onto the floor the last few drops that remained: this was an act of gratitude to the gods, and it was almost universal in its application. Our mishnah makes clear, however, that a soldier who steals a cup of wine from an open cask is in too much of a hurry to keep up with his company to offer the libation, so the wine need not be considered yeyn nesekh.
