Gemara

12a: If one blessed Birkas ha'Mazon on dates, he was Yotzei.

This is because dates give sustenance (like bread).

35b: A small amount of wine sustains.

Question: If so, we should say Birkas ha'Mazon after wine!

Answer: We do not, for it is abnormal to base a meal on wine.

Question (Rav Nachman bar Yitzchak): If one bases a meal on wine, what is the law?

Answer (Rava): We are not concerned for his mindset. The Halachah is based on normal people.

41b (Rav Huna and Rav Nachman): If figs and grapes were served in a meal, one blesses on them beforehand, but not afterwards;

(Rav Sheshes): He blesses on them beforehand and afterwards;

(Rav Papa): The Halachah is, things eaten due to the meal during the meal do not require a blessing beforehand or afterwards;

Things eaten not due to the meal require a blessing beforehand, but not afterwards;

Things normally eaten after the meal require a blessing beforehand and afterwards.

48a: Shimon ben Shetach drank a cup of wine, and blessed (Birkas ha'Mazon for everyone).

R. Aba: This is (only) his opinion;

(R. Chiya bar Aba): One may not be Motzi others (in Birkas ha'Mazon) unless he ate a k'Zayis of grain.

Pesachim 103a: Rav Yeiva the elder was serving Rav Beruna and Rav Chananel. They told him 'give us (wine) and we will bless (Birkas ha'Mazon)'! They reconsidered and said 'give to us (wine) to drink.'

Rav Yeiva: Rav says that once you said that you will bless, you may no longer drink!

Rishonim

Rosh (1:14): Dates sustain, therefore one who ate dates is Yotzei through Birkas ha'Mazon. This does not apply to the other seven (some texts - five) species. R. Yonah brings from Tosfos that the same applies to wine. Also, even if he said only Birkas ha'Zan, whether for wine or dates, he was Yotzei. I agree, but only if he concluded Baruch Atah Hash-m (Elokeinu Melech ha'Olam - Ma'adanei Yom Tov deletes this from the text, for we do not mention Malchus in the closing of Berachos) ha'Zan Es ha'Kol. One may bless only one Berachah afterwards.

Ma'adanei Yom Tov (70): Since people do not fix meals on it, we cannot say three Berachos.

Rosh (ibid.): However, if he said the entire text until Baruch Atah Hash-m ha'Zan, but did not conclude, he begins "v'Al she'Hinchalta la'Avoseinu..." and concludes with Birkas me'Ein Shalosh. The text of Birkas ha'Zan is in place of Al ha'Etz v'Al Borei Peri ha'Etz.

Beis Yosef (OC 208 DH Kasav): One can challenge this from the Yerushalmi, in which R. Chiya bar Ashi told Rav Huna to leave his dates for after the Mazon, to bless on them before and after. I.e. he would eat them after the meal, and before Birkas ha'Mazon, and Birkas ha'Mazon will not exempt dates. However, perhaps this is only l'Chatchilah, but b'Di'eved Birkas ha'Mazon exempts them.

R. Yonah (29b DH l'Echad): After the meal, when he eats (other foods) without bread, he must make the proper Berachah before and after. The Tosafists learn from here that Birkas ha'Mazon does not exempt me'Ein Shalosh. If one ate porridge or similar matters after the food (bread), even though its Berachah is similar to Birkas ha'Mazon, Birkas ha'Mazon does not exempt it. If Birkas ha'Mazon did exempt it, we would not bless after it! However, it seems that wine is different. After saying 'let us bless' one may not drink without a Berachah (Pesachim 103b). He blesses before, but not after. For wine, Birkas ha'Mazon exempts me'Ein Shalosh, even if he did not bless Birkas ha'Mazon on a cup of wine. Berachos 35b supports this. Since wine sustains, we should say Birkas ha'Mazon after wine. We do not, only because people do not base meals on wine. Therefore, it is proper that Birkas ha'Mazon exempt wine more than other foods.

R. Yonah (6a DH Iy): The Tosafists say that also regarding wine, if one forgot and blessed Birkas ha'Mazon in place of me'Ein Shalosh, he was Yotzei. The Gemara suggested that we should say Birkas ha'Mazon after wine. The Gemara did not suggested this regarding dates. This shows that it was more obvious that wine sustains than that dates sustain. Since b'Di'eved Birkas ha'Mazon exempts dates, similarly it exempts wine. Even if he said only Birkas ha'Zan, for wine or dates, he was Yotzei. Even though this has the essence of only one Berachah, and me'Ein Shalosh has the essence of three Berachos, since we say that he was Yotzei due to Mazon (it sustains), he was Yotzei even with Birkas ha'Zan alone.

Tosfos (103a DH Ana): Since Birkas me'Ein Shalosh exempts wine, all the more so Birkas ha'Mazon exempts it. Bahag says so. However, this is not a Kal va'Chomer. We hold (41b) that matters not due to the meal, if eaten after the meal and before Birkas ha'Mazon, require a Berachah before and after. Rav Sheshes says so even for figs and grapes in a meal. Rashi says so in a Teshuvah. However, it seems that the Halachah follows Rav Papa, that they require a Berachah Acharonah only if they are after the meal.

Poskim

Shulchan Aruch (OC 208:17): Birkas ha'Mazon does not exempt me'Ein Shalosh. If one ate porridge, Birkas ha'Mazon does not exempt it.

Taz (18): The Shulchan Aruch discusses porridge after the meal. Surely Birkas ha'Mazon exempts porridge during the meal. Birkas ha'Mazon does not exempt Borei Nefashos.

Magen Avraham (25): Even though porridge sustains like wine and dates, it is has a more important form (bread. Therefore, Birkas ha'Mazon does not exempt it.)

Kaf ha'Chayim (87): The Pri Chodosh says that the Shulchan Aruch is like R. Yonah, but this is unreasonable. Porridge sustains more than dates. Therefore, Birkas ha'Mazon exempts the five grains. Be'er ha'Golah and Machazik Berachah agree, and Eliyahu Rabah says that the Rosh and Rashba connote like this.

Mishnah Berurah (75): The same applies to other cooked dishes from the five grains. Even though they sustain more than dates, since they have a more important form, i.e. bread, Birkas ha'Mazon is only for bread (but not for anything else from the five grains). Several Acharonim hold unlike the Mechaber, that b'Di'eved Birkas ha'Mazon exempts them. Since they sustain, they are no worse than dates. All the more so, Birkas ha'Mazon surely exempts Pas ha'Ba b'Kisnin (cake or wafers).

Shulchan Aruch (ibid.): However, Birkas ha'Mazon exempts wine. Similarly, if one blessed Birkas ha'Mazon on dates in place of Al ha'Etz, he was Yotzei.

Beis Yosef (DH veha'Rashba): The Rashba (41b) says that presumably, even Rav Sheshes (who obligates blessing after figs and grapes in a meal) does not obligate blessing after dates, for they sustain, so Birkas ha'Mazon exempts them. The Yerushalmi (cited above) connotes otherwise. Perhaps the Yerushalmi is like Rav Muna said there in the name of R. Yosi ha'Glili. However, Bahag says that Birkas ha'Mazon does not exempt dates, pomegranates and other fruits. The Rashba (48a DH Ha) says that the Sugya of figs and grapes in the meal proves that Birkas ha'Mazon does not exempt me'Ein Shalosh. Shimon ben Shetach is a lone dissenting opinion. Alternatively, wine is different, like it says on 35b, like the Gemara said about dates.

Bi'ur Halachah (DH Aval): There are several opinions about wine. 1) R. Yonah and the Rosh hold that if one drank wine not in a meal and blessed Birkas ha'Mazon, b'Di'eved he exempted the wine. It seems that the Rashbam and Ba'al ha'Ma'or agree. The Ramban and Ran hold that Birkas ha'Mazon does not exempt wine, but the Halachah does not follow them. 2) If one drank after the meal, R. Yonah, the Rashbam and Ba'al ha'Ma'or say that Birkas ha'Mazon automatically exempts it, even without explicit intent. The Rosh, Ramban and Ran hold that one must bless after the wine, and not rely on Birkas ha'Mazon. (If one did, the Rosh and those with him mentioned above hold that it helped, and the Ramban and Ran disagree). This is not relevant for us, since we consider everything (even what is after the meal) as if it is in the meal, unless he said 'let us bless.' Then, it depends on these opinions. Therefore, he should explicitly intend to exempt it through Birkas ha'Mazon, and he is Yotzei according to most Poskim. 3) If he drank only before the meal, the Ba'al ha'Ma'or, Ramban and Ran say that Birkas ha'Mazon does not exempt it, but the Rosh holds that l'Chatchilah (perhaps this should say 'automatically' - PF) Birkas ha'Mazon exempts it, for wine arouses appetite, so it is part of the meal. The Shulchan Aruch (174:6) rules like him. Surely, one does not veer from the Shulchan Aruch's ruling, but l'Chatchilah one should explicitly intend to exempt the wine that he drank. (This helps according to the Ba'al ha'Ma'or.)

Kaf ha'Chayim (88): If one ate dates or wine or the five grains, and now he will eat bread, l'Chatchilah he should bless me'Ein Shalosh first. If he already said ha'Motzi, he intends that Birkas ha'Mazon exempt also what he ate beforehand.

Kaf ha'Chayim (89): Similarly, if one said Al ha'Michyah for wine or dates, he was Yotzei, but Al ha'Michyah does not exempt figs.

Shulchan Aruch (ibid.): Even if he said only Birkas ha'Zan, whether for wine or dates, he was Yotzei. If he remembered before he finished Birkas ha'Zan, he begins "v'Al she'Hinchalta la'Avoseinu..." and concludes with Birkas me'Ein Shalosh.

Gra (DH v'Im): L'Chatchilah one may not say Birkas ha'Mazon (for dates or wine), and he should not even exempt them through Birkas ha'Mazon (if he ate them before a meal. Rather, he blesses first me'Ein Shalosh.) The Halachah does not follow Shimon ben Shetach.

Bi'ur Halachah (DH Ela): Why is he Yotzei without Birkas ha'Aretz and Boneh Yerushalayim? We must say that they enacted to include all three matters (Mazon, the land and Yerushalayim) only l'Chatchilah. B'Di'eved, it suffices if he mentioned just ha'Mazon. I later found that R. Yonah proved from here that Birkas me'Ein Shalosh is mid'Rabanan. According to the opinion that it is mid'Oraisa, this requires investigation.

Kaf ha'Chayim (90): If he remembered in time, he concludes me'Ein Shalosh, for l'Chatchilah one must mention the essence of all three Berachos.