Eight of those players were spread out across Europe, while Said Benrahma and Michail Antonio were plying their trade in Africa and Central America respectively.
Here, Sports Mole round up which Hammers players were in action for their respective nations and how they fared on international duty.
England: Declan Rice
Results:
September 2: Hungary 0-4 England - World Cup qualifier (Ferenc Puskas Stadium, Budapest)
September 5: England 4-0 Andorra - World Cup qualifier (Wembley Stadium, London)
September 8: Poland 1-1 England - World Cup qualifier (Stadion Narodowy, Warsaw)
Just moments before being substituted in the 88th minute, Rice scored his second international goal when he tucked away England's fourth in Hungary, before being rested against Andorra.
The 22-year-old midfielder then played the full 90 minutes against Poland, though the Three Lions were unable to maintain their 100% record in qualifying, conceding a stoppage-time equaliser in Warsaw.
Czech Republic: Tomas Soucek, Vladimir Coufal, Alex Kral
Results:
September 2: Czech Republic 1-0 Belarus - World Cup qualifier (Mestsky stadion,Ostrava-Vitkovice)
September 5: Belgium 3-0 Czech Republic - World Cup qualifier (King Baudouin Stadium, Brussels)
September 8: Czech Republic 1-1 Ukraine - Friendly (Doosan Arena, Plzen)
All three players started in the narrow win against Belarus, though deadline day signing Kral was dropped to the bench against Belgium and came on as a substitute in the 76th minute.
Against Ukraine, all three were named in the starting lineup again, with Soucek brought off in the 62nd minute.
Ukraine: Andriy Yarmolenko
Results:
September 1: Kazakhstan 2-2 Ukraine - World Cup qualifier (Astana Arena, Nur-Sultan)
September 4: Ukraine 1-1 France - World Cup qualifier (NSC Olimpiyskiy, Kiev)
September 8: Czech Republic 1-1 Ukraine - Friendly (Doosan Arena, Plzen)
Yarmolenko, earning his 102nd Ukraine cap, also started the game in Plzen, as well as the two World Cup qualifiers, though the winger was unable to help his national side claim a victory during this month's international break.
Spain: Pablo Fornals
Results:
September 1: Sweden 2-1 Spain - World Cup qualifier (Friends Arena, Stockholm)
September 5: Spain 4-0 Georgia - World Cup qualifier (Estadio Nuevo Vivero, Badajoz)
September 8: Kosovo 0-2 Spain - World Cup qualifier (Fadil Vokrri Stadium, Pristina City)
Fornals, who earned his first international call up since the winter of 2018, was an unused substitute in the defeat to Sweden, however he did come off the bench against Georgia in the 60th minute.
Just three minutes after entering the field of play, the 25-year-old provided the assist for Spain's fourth goal scored by Pablo Sarabia.
Then against Kosovo, Fornals scored his first senior goal on his first start for Spain, breaking the deadlock in the 32nd minute with a powerful left-footed strike at the near post.
France: Kurt Zouma
Results:
September 1: France 1-1 Bosnia & Herzegovina - World Cup qualifier (Stade de la Meinau, Strasbourg)
September 4: Ukraine 1-1 France - World Cup qualifier (NSC Olimpiyskiy, Kiev)
September 7: France 2-0 Finland - World Cup qualifier (Parc Olympique Lyonnais, Lyon)
Zouma was an unused substitute in the draw against Bosnia & Herzegovina, but played the full 90 minutes in the next two qualifiers, making his 10th international appearance in Lyon.
The 25-year-old started in a back four against Ukraine before playing on the right side of a back three against Finland, joining fellow centre-backs Raphael Varane and Presnel Kimpembe in the heart of the defence.
Croatia: Nikola Vlasic
Results:
September 1: Russia 0-0 Croatia - World Cup qualifier (Luzhniki Stadium, Moscow)
September 4: Slovakia 0-1 Croatia - World Cup qualifier (Tehelne Pole, Bratislava)
September 7: Croatia 3-0 Slovenia - World Cup qualifier (Stadion Poljud, Split)
Vlasic, who joined the Hammers on deadline day, will have been keen to impress on international duty before flying to London to join his new teammates later this month.
The 23-year-old played the full 90 minutes in the goalless draw with Russia before coming off in the 55th minutes against Slovakia.
Vlasic then started on the bench against Slovenia but came on as a substitute for the final half an hour and found the net with a diving header in added time, scoring his seventh international goal, to seal a comfortable victory in the midfielder's home city of Split.
Algeria: Said Benrahma
Results:
September 2: Algeria 8-0 Djibouti - World Cup qualifier (Stade Mustapha Tchaker, Blida)
September 7: Burkina Faso 1-1 Algeria - World Cup qualifier (Stade de Marrakech, Marrakech)
Benrahma came off the bench in both qualifiers, playing the final 30 minutes against Djibouti, before entering the field of play in the 67th minute against Burkina Faso, a game in which former Hammers winger Sofiane Feghouli was on target for the visitors.
Jamaica: Michail Antonio
Results:
September 5: Jamaica 0-3 Panama - World Cup qualifier (Independence Park, Kingston)
Antonio did not travel to Mexico and Costa Rica for Jamaica's qualifiers, as both countries are currently on the red travel list amid the ongoing coronavirus pandemic.
The 31-year-old was, however, able to make his first international appearance in the defeat to Panama, playing 70 minutes.