ฝรั่งเศสเลือกที่จะเข้าปากแม่น้ำหลังพระอาทิตย์ตกดินในวันที่ 13 กรกฎาคม
<!--The French chose to cross the bar just after sunset on July 13, their objective was to fight there way past the Siamese defenses but only if fired upon. The weather was overcast. By this time the Siamese were on high alert and at battle stations. The French ships were towed into action by the small mail [[steamboat|steamer]] [[Jean Baptiste Say (steamship)|''Jean Baptiste Say'']]. At 6:15 pm the rain stopped and the Siamese gunners observed the French ships passing the nearby [[lighthouse]]. A few minutes later, the French were off Black Buoy when they entered the range of the fort. Siamese gunners were ordered to fire three warning shots, if they were ignored, then a fourth would signal their gunboats to begin firing.
At 6:30, the fort opened fire with two blank rounds but the French continued on so a third, live, warning shot was fired and hit the water in front of the ''Jean Baptiste Say''. When this warning was ignored a fourth shot was fired so the gunboats ''Makhut Ratchakuman'' and ''Muratha Wasitsawat'' opened up at 6:50. ''Inconstant'' returned fired on the fort while the ''Comete'' engaged the gunboats. A small boat filled with explosives was also sent out to ram one of the French ships but it missed it's target. Combat lasted about twenty-five minutes.
Ultimately Rear Admiral Humann forced his way through the Siamese line, ramming and sinking one gunboat in the process. One other was hit by shell fire, ten men were killed and twelve others wounded. The French suffered as well, while towing the warships past Paknam, the ''Jean Baptiste Say'' was hit several times by cannon fire. Her commander was forced to cut the tow line and ground his ship on Laem Lamphu Rai while the ''Inconstant'' and ''Comete'' proceeded onto Bangkok. Three Frenchmen were killed and two others were wounded. ''Comete'' received more hits than the ''Inconstant'' but the damage was not serious. The Siamese fort was not damaged.